# The Digital Trail

An episode of [What Happened To…](https://invisiblenetwork.ai/podcast/1812362613), 27 Sep 2026, 21 min.

Audio: https://p.podderapp.com/2544644999/traffic.omny.fm/d/clips/2fb3740d-3436-44af-8cc0-a91900716aa5/8c185e62-46f1-4292-81b7-b2d00059655d/8b7990ba-38f8-47f7-b699-b4cd006cb91f/audio.mp3?utm_source=Podcast&in_playlist=fcf80ea6-cd25-4daa-b194-b2d000596ad2

As the investigation into Samantha Murphy’s disappearance intensified, police were not only searching the ground — they were also following a digital trail. Telecommunications expert Associate Professor Mark Gregory explains how mobile phones, smartwatches and tower data can help investigators map movements, identify devices in an area and look for unusual patterns. We examine how this kind of digital evidence may have helped police piece together crucial parts of the investigation. IMPORTANT NOTE: This episode was originally recorded and published during the early stages of the investigation and reflects information publicly available at that time. Since its original publication, criminal proceedings relating to Samantha Murphy’s disappearance have commenced. This episode has not been updated to discuss those proceedings and does not address the person currently before the courts, the evidence in those proceedings, or questions of guilt or innocence. Nothing in this episode should be interpreted as commenting on, prejudging or seeking to influence any current court proceedings. The accused is presumed innocent unless and until proven guilty according to law. See omnystudio.com/listener for privacy information.

## Transcript

[0:05] Speaker 1: A Poche Production.
[0:13] Speaker 2: Welcome back to What Happened to Samantha Murphy. A person
[0:16] Speaker 2: has been arrested and charged for Samantha's alleged murder in 2024.
[0:20] Speaker 2: There was an original suppression order on the accused person
[0:25] Speaker 2: and it was lifted back in 2024. He's since been
[0:29] Speaker 2: named as now 24-year-old Patrick Stevenson. In this podcast, we
[0:33] Speaker 2: make no assertions that Mr Stevenson had anything to do
[0:36] Speaker 2: with Samantha's disappearance. This podcast is a retelling of the
[0:40] Speaker 2: show that was initially released in 2024 at the time
[0:44] Speaker 2: of Samantha's disappearance.
[0:46] Speaker 3: Detectives from the Missing Persons Squad yesterday morning at 6am
[0:50] Speaker 3: arrested a 22-year-old Scottsburn man. They arrested him at his
[0:55] Speaker 3: home address and took him into custody. The man was
[0:58] Speaker 3: interviewed over a number of hours. A number of search
[1:01] Speaker 3: warrants have been executed. As a result of those investigations,
[1:06] Speaker 3: he has today been charged with the murder of Samantha.
[1:10] Speaker 3: We will be alleging that murder occurred at Mount Clare
[1:14] Speaker 3: on the day she disappeared.
[1:16] Speaker 2: In the next episode, we're going to look at all
[1:17] Speaker 2: we know about the allegations around 22-year-old Patrick Stevenson.
[1:21] Speaker 1: Yes, we can now reveal the accused is 22-year-old Patrick Stevenson,
[1:25] Speaker 1: the son of former AFL player Oren Stevenson, who played
[1:28] Speaker 1: for Richmond and Geelong. The 22-year-old was arrested at a
[1:32] Speaker 1: Scottsburn address on Wednesday morning and subsequently charged with murder.
[1:36] Speaker 1: He fronted court for the first time yesterday and a
[1:39] Speaker 1: suppression order was placed on his identity. But this morning,
[1:42] Speaker 1: the media fought that suppression order and now... We can
[1:45] Speaker 1: name him.
[1:47] Speaker 2: But before we get there, we want to try and
[1:49] Speaker 2: follow the steps police might have followed in trying to
[1:52] Speaker 2: track down Samantha's alleged killer. I want to be very clear.
[1:55] Speaker 3: I'm limited in what I can say, given that they're
[1:58] Speaker 3: housed now being a charge of murder laid.
[2:00] Speaker 2: We know the police and volunteers did extensive searches on
[2:03] Speaker 2: the ground for Sam. But what we didn't see is
[2:06] Speaker 2: the digital tracks police were following.
[2:08] Speaker 3: Those detectives from the missing persons unit who've worked very
[2:12] Speaker 3: long hours, intensive hours since this occurred. They've been assisted
[2:17] Speaker 3: by other members from crime command, other detectives from there,
[2:21] Speaker 3: those from the Western region, as well as detectives from
[2:25] Speaker 3: our counter-terrorism command to make sure we had significant resources
[2:29] Speaker 3: to solve this case.
[2:31] Speaker 2: It's highly likely those digital tracks led to the arrest
[2:34] Speaker 2: of Stevenson. And in this episode, We're going to try
[2:38] Speaker 2: and put together those missing pieces with an expert in
[2:41] Speaker 2: the field of mobile phone surveillance.
[2:43] Speaker 4: So I'm Associate Professor Mark Gregory from the School of
[2:45] Speaker 4: Engineering at RMIT University and I work in the area
[2:50] Speaker 4: of telecommunications, networking and security.
[2:53] Speaker 2: You've been reasonably vocal about your thoughts on what police
[2:57] Speaker 2: would be doing in their efforts to find sort of
[3:00] Speaker 2: the last locations for Sam and equally anyone else in
[3:04] Speaker 2: the area at the time.
[3:05] Speaker 4: Yes, I think that the police will have been utilising
[3:11] Speaker 4: technology as one of their forensic tools with a view
[3:14] Speaker 4: to identifying people in the area and possibly movements of
[3:22] Speaker 4: Samantha Murphy's mobile through that area.
[3:25] Speaker 2: I'm guessing police have access, wide-ranging access, across telecommunication companies.
[3:31] Speaker 2: Let's firstly talk about Sam's mobile. We know that she
[3:34] Speaker 2: had a mobile phone with her. We know that she
[3:36] Speaker 2: had her Apple Watch with her as well. What sort
[3:40] Speaker 2: of data are they getting back from phones and mobile
[3:44] Speaker 2: watches in this particular case, do you think?
[3:47] Speaker 4: So I think in this particular case, the first thing
[3:49] Speaker 4: that the police would have looked at is the records
[3:53] Speaker 4: of the telecommunication companies. So what they're really first trying
[3:57] Speaker 4: to identify is have the devices been registered on the network,
[4:01] Speaker 4: where and when. And often today, depending upon the technology
[4:06] Speaker 4: on the mobile towers, we can get general indications and
[4:10] Speaker 4: distances that those devices were from the tower. And really
[4:16] Speaker 4: in the case of what we saw happened in the
[4:20] Speaker 4: area of Buninyong, They're really looking at trying to find
[4:24] Speaker 4: information off towers that are around that area. And so
[4:29] Speaker 4: towers that are on major access to the area and
[4:34] Speaker 4: also towers in the vicinity. So there's no logical placement
[4:39] Speaker 4: of towers. Towers are often placed where customers are alongside
[4:43] Speaker 4: roads and roads. you know, on high locations. And so
[4:48] Speaker 4: they can be quite dispersed. And so the police would
[4:51] Speaker 4: be looking for information from, you know, towers in the
[4:54] Speaker 4: general vicinity of the forest.
[4:57] Speaker 2: Am I right in saying that although that area is
[5:01] Speaker 2: bushland and heavy bushland, there was still reasonable phone service,
[5:05] Speaker 2: if you like, tower coverage across that whole bushland?
[5:09] Speaker 4: So there is coverage in many of the areas around
[5:15] Speaker 4: sort of those urban centres such as Ballarat. We find
[5:20] Speaker 4: that there are pockets, if you like, of areas where
[5:25] Speaker 4: the coverage is poor, such as gullies or areas where
[5:28] Speaker 4: there's a lot of trees. And this can be affected,
[5:32] Speaker 4: of course, by the weather at the time, heat, solar radiation. rain,
[5:39] Speaker 4: dust in the air, and so forth. So there's a
[5:42] Speaker 4: number of variables that would come into play in terms
[5:46] Speaker 4: of the coverage. And of course, we need to remember
[5:49] Speaker 4: that the device would need to be operating with enough
[5:54] Speaker 4: battery for the device to operate normally.
[5:59] Speaker 2: Do we know what service provider Sam's phone was on?
[6:04] Speaker 2: I'm with a particular company that doesn't get great service
[6:07] Speaker 2: when I'm You know, in regional remote areas, however, there
[6:11] Speaker 2: are a couple of other service providers that are a
[6:13] Speaker 2: stronger reach. Do we know who Sam's provider was at
[6:17] Speaker 2: the time or does that not matter?
[6:19] Speaker 4: It doesn't matter other than the ability of that person to,
[6:25] Speaker 4: you know, to operate the phone. Phones still have the
[6:29] Speaker 4: ability to camp on to the other networks for triple
[6:34] Speaker 4: O calls. And so the devices are generally identified, even
[6:41] Speaker 4: if they're from a different provider. What you generally tend
[6:45] Speaker 4: to find is that in regional and, you know, remote
[6:49] Speaker 4: areas at this stage, you know, Telstra is the dominant provider.
[6:54] Speaker 4: But that, you know, of course doesn't mean that Samantha
[6:56] Speaker 4: Murphy might not have been with another provider.
[7:00] Speaker 2: So what we're saying there really is if she was
[7:03] Speaker 2: with a provider that didn't have service in that particular area,
[7:06] Speaker 2: it doesn't matter because police were still able to ping
[7:09] Speaker 2: that phone no matter whether it had service or not.
[7:13] Speaker 2: Is that fair?
[7:13] Speaker 4: Yeah, the devices will generally be registered onto the towers
[7:17] Speaker 4: so that the devices are known in case the device
[7:23] Speaker 4: is going to make a triple O call or something,
[7:25] Speaker 4: even if it's from a different service provider.
[7:28] Speaker 2: And how good is the tracking technology police would use
[7:33] Speaker 2: to be able to pinpoint a location? Obviously, they've said
[7:36] Speaker 2: that the last known ping from Sam's phone was about
[7:39] Speaker 2: seven kilometres away from her house in that area of
[7:42] Speaker 2: the Canadian State Forest. How pinpoint accurate are those types
[7:49] Speaker 2: of pings, if you like?
[7:51] Speaker 4: Well, depending upon the antennas that are being used on
[7:54] Speaker 4: the towers, whether it's 3G, 4G and 5G, and the
[8:00] Speaker 4: number of towers, of course, you can get information about
[8:05] Speaker 4: direction and distance from the towers. But generally in regional areas,
[8:12] Speaker 4: that becomes more difficult. Now, with the older omnidirectional towers,
[8:18] Speaker 4: where the signal is broadcast in a circle radiating out
[8:22] Speaker 4: from the tower, then finding the direction if there's only
[8:26] Speaker 4: one tower is quite difficult. It does record the signal
[8:31] Speaker 4: strength to the device and that will generally give you
[8:34] Speaker 4: an indication of how far away from the tower the
[8:38] Speaker 4: device is. However, the direction is something that depends upon
[8:44] Speaker 4: the antenna configuration and With the 4G antenna configurations, we
[8:50] Speaker 4: are able to narrow it down to an area in
[8:56] Speaker 4: a particular direction from the tower with the newer antennas.
[9:01] Speaker 4: And so depending upon the towers in that area, the
[9:05] Speaker 4: police would have been looking for that information.
[9:08] Speaker 2: Does the smartwatch also help in this circumstance where, so
[9:11] Speaker 2: depending whether the smartwatch had a SIM card in it
[9:14] Speaker 2: or not, would be whether that's sending its own signal?
[9:17] Speaker 4: Oh, most certainly. If the watch was mobile enabled, then
[9:25] Speaker 4: that watch would be talking to the network as well.
[9:29] Speaker 4: And the network would have identified that watch separately to
[9:36] Speaker 4: the phone. And so it may be possible that the
[9:40] Speaker 4: phone might have been turned off. However, the watch might
[9:44] Speaker 4: have been accidentally left on. People may not realise that
[9:49] Speaker 4: it is actually connecting to the network. And so therefore,
[9:55] Speaker 4: you're going to have this connection to the network from
[9:57] Speaker 4: the watch.
[9:59] Speaker 2: A lot of experts agree that this digital footprint of
[10:02] Speaker 2: Samantha's movements was crucial in localisation. her last known position.
[10:07] Speaker 2: That position, as we now know, was seven kilometres from
[10:10] Speaker 2: where Sam left her house on the morning of the
[10:14] Speaker 2: 4th of February, a location just near Clear Mountain. What
[10:19] Speaker 2: we didn't know at the time was was that Stevenson's
[10:22] Speaker 2: family home was just across the road from the parklands
[10:26] Speaker 2: at Mount Clear. So Sam's phone and watch possibly plays
[10:31] Speaker 2: a pivotal role in tracking down her movements, but Mark
[10:35] Speaker 2: was vocal about one other piece of information that was important.
[10:41] Speaker 2: And that was, what about the other phones and digital
[10:44] Speaker 2: devices that were in the same vicinity, connected to the
[10:48] Speaker 2: same phone towers?
[10:50] Speaker 3: Well, yes.
[10:51] Speaker 4: From the police point of view, what they're trying to
[10:53] Speaker 4: do is to identify all those people in the area
[10:58] Speaker 4: at the time when Samantha Murphy went missing. And so
[11:03] Speaker 4: they will look at all of the devices that connected
[11:06] Speaker 4: to the towers in the vicinity of that forest. Now,
[11:11] Speaker 4: my understanding is that Samantha Murphy would run about 10 kilometres.
[11:17] Speaker 4: So we're talking quite a distance. And that could mean
[11:23] Speaker 4: quite a few towers in that area. Plus, of course,
[11:26] Speaker 4: the towers on the roads leading to and from that area.
[11:29] Speaker 4: And you're not that far away from a major regional centre.
[11:33] Speaker 4: So therefore, that complicates matters in the number of towers. However,
[11:37] Speaker 4: police would have formed a task force that would be
[11:40] Speaker 4: aware of what they've got to do. They would get
[11:42] Speaker 4: the information from all the towers. And then they would
[11:46] Speaker 4: start looking through that information. And there would be a
[11:49] Speaker 4: combination of desk workers who are going to be looking
[11:53] Speaker 4: at information and trying to correlate with the people that
[11:56] Speaker 4: live in the area. What are their normal activities in
[12:00] Speaker 4: the area? And looking for anomalies. And there will be
[12:03] Speaker 4: people that would be doing computer processing of the data
[12:07] Speaker 4: to look, you know, to use scripts and other techniques
[12:11] Speaker 4: to manipulate the data to look for anomalies and discrepancies.
[12:17] Speaker 4: And one example of what they might be doing is
[12:21] Speaker 4: they might be looking at the situation where that young
[12:25] Speaker 4: lady was attacked in the area about a year ago
[12:29] Speaker 4: and trying to use that information from a year ago
[12:34] Speaker 4: and correlate with what happened this time. to see if
[12:38] Speaker 4: there's outcomes where you might have a device appear in
[12:42] Speaker 4: that area only on those two days or near those
[12:46] Speaker 4: two events. And that then would make that device one
[12:51] Speaker 4: that was of interest to police. And so you're looking
[12:55] Speaker 4: for anomalies. You're looking for things out of the ordinary.
[12:58] Speaker 4: But also it can be just quite simple in that
[13:01] Speaker 4: if there was foul play, then it could be someone
[13:05] Speaker 4: living in the area. And so you really want to
[13:08] Speaker 4: know who is in the area at the time.
[13:11] Speaker 2: A reminder that Sissy Austin was the woman who was
[13:13] Speaker 2: attacked in the same general area as Sam about a
[13:17] Speaker 2: year before. Sissy has been really vocal on her social
[13:20] Speaker 2: media about this case, and in particular that her case
[13:24] Speaker 2: a year ago didn't feel like it was investigated properly.
[13:28] Speaker 2: Would telecommunication companies have all of that data still, even
[13:33] Speaker 2: though it was a year ago?
[13:34] Speaker 4: Most certainly. Under the current legislation, the information is required
[13:40] Speaker 4: to be kept for a number of years. And so
[13:43] Speaker 4: that information would be available to police if requested in
[13:47] Speaker 4: the appropriate way through their online systems and with a warrant.
[13:52] Speaker 4: That information would be made available to police.
[13:56] Speaker 2: We don't know if Sissy and Samantha's cases are connected.
[14:00] Speaker 2: There seems to be a lot of similarities. Our mobile
[14:04] Speaker 2: phone expert thinks that police may have looked back at
[14:08] Speaker 2: data from a year ago from the digital footprint.
[14:11] Speaker 4: In the area. Where you have screened different events and
[14:16] Speaker 4: time periods, you would be using computer scripts to look
[14:22] Speaker 4: for correlations and similarities that you might then follow up.
[14:27] Speaker 2: And am I right in saying everybody's mobile phone these
[14:32] Speaker 2: days is attached to them for the most part? You
[14:35] Speaker 2: need a license to get a mobile phone. You need
[14:38] Speaker 2: to prove your identity. And every phone has its own
[14:42] Speaker 2: serial number, if you like, an IME number.
[14:44] Speaker 4: So in Australia, to get a mobile, of course, you've
[14:50] Speaker 4: got to have two things. One is you've got to
[14:52] Speaker 4: have the device. And the second thing is you've got
[14:54] Speaker 4: to have a connection to a network. And Under Australian legislation,
[14:58] Speaker 4: to get the connection to the network, you have to
[15:01] Speaker 4: be identified. Now, of course, you may have companies that
[15:07] Speaker 4: buy devices or pay for company plans. You have individuals, organisations.
[15:15] Speaker 4: We're familiar, of course, in the movies with this idea
[15:18] Speaker 4: of a burner phone, where someone just goes into a
[15:20] Speaker 4: store and grabs a phone and away they go type
[15:24] Speaker 4: of thing, right? But that's Not something that's easily done
[15:28] Speaker 4: in Australia. That's not to say that criminal organisations don't
[15:32] Speaker 4: work very hard to get access to phones that are
[15:36] Speaker 4: not linked to them individually. But it is more difficult
[15:40] Speaker 4: in Australia. Of course, one of the problems that we
[15:44] Speaker 4: do see is that we have this system called international roaming.
[15:50] Speaker 4: And so that means that you can get a SIM
[15:52] Speaker 4: card in another country that will still operate in Australia,
[15:56] Speaker 4: you know, utilising this thing called international roaming. So it's
[16:00] Speaker 4: not an Australian SIM card. You know, you would have
[16:02] Speaker 4: a similar effect, not exactly the same, but a similar
[16:07] Speaker 4: effect to what we call these burner phones. You know,
[16:09] Speaker 4: what you do is you pick up some SIM cards
[16:12] Speaker 4: in a country which doesn't have the same laws as Australia,
[16:16] Speaker 4: which requires... a high degree of identification and you bring
[16:22] Speaker 4: those SIM cards back to Australia and utilise those SIM cards. Now,
[16:27] Speaker 4: of course, that's going to be a more expensive approach
[16:29] Speaker 4: because those SIM cards do come from another country and
[16:33] Speaker 4: you are utilising those SIM cards through international roaming. But
[16:40] Speaker 4: for some people, that cost is marginal for their activities.
[16:45] Speaker 2: If this was an opportunistic attack, then you wouldn't imagine
[16:48] Speaker 2: that someone would go to the trouble of turning their
[16:52] Speaker 2: mobile phone off, for instance, or getting an international SIM
[16:57] Speaker 2: card or getting a burner phone. That doesn't seem that likely. However,
[17:02] Speaker 2: if it was a planned attack, if someone had followed Sam,
[17:07] Speaker 2: been watching her movements, knowing that she was running in
[17:10] Speaker 2: that particular area, they might be able to evade some
[17:14] Speaker 2: of the some of the digital footprint that we've been
[17:17] Speaker 2: talking about?
[17:18] Speaker 4: Most certainly. Look, you don't know the circumstances behind what's
[17:24] Speaker 4: happened at this point. And we don't know, you know,
[17:31] Speaker 4: what was actually the motivation if there are other people
[17:37] Speaker 4: actually involved in this matter. But we don't or shouldn't
[17:42] Speaker 4: discount the in the modern world, inability to Google and
[17:48] Speaker 4: to learn very quickly about how they might utilise technology
[17:53] Speaker 4: that will frustrate the Australian police effort.
[18:00] Speaker 3: This investigation is far from over though. Obviously, we're going
[18:04] Speaker 3: to be continuing to gather further evidence, we'll be taking
[18:08] Speaker 3: further statements and investigations will continue at a very heavy pace. Importantly,
[18:16] Speaker 3: doing everything we can to locate Samantha's body for the
[18:20] Speaker 3: family is absolutely vital and something we'll be focusing on.
[18:26] Speaker 3: But anyone who has any information, even the slightest bit
[18:30] Speaker 3: of information that you think might not be that relevant,
[18:33] Speaker 3: please call Crime Stoppers on 1800 333 000.
[18:35] Speaker 4: Any little clue.
[18:41] Speaker 3: Could be vital in helping us locate her body.
[18:52] Speaker 2: In the next episode of Missing Pieces, the search for
[18:55] Speaker 2: Samantha Murphy, we speak with Damien Marrett. He's a former
[18:58] Speaker 2: Victorian police detective and he breaks down the arrest and
[19:01] Speaker 2: allegations against Patrick Stevenson.
[19:05] Speaker 5: If he was, say, at the parents' house around the
[19:08] Speaker 5: time that this happened, and remember, he probably is visiting
[19:11] Speaker 5: the parents' house back and forward, depending on where he
[19:14] Speaker 5: permanently lives. But I'd say the police would have searched
[19:19] Speaker 5: the parents' house as well, would have searched the house
[19:22] Speaker 5: that he's staying in, would have even searched the girlfriend's house.
[19:26] Speaker 5: Something sort of changed in the way police were carrying
[19:30] Speaker 5: out their media briefings. Sort of in that... two to
[19:34] Speaker 5: three week period they sort of pulled back a lot
[19:37] Speaker 5: from the searches they went less vocal and so I
[19:42] Speaker 5: would say something's happened around that time for them to
[19:45] Speaker 5: start looking very closely at this guy if you haven't
[19:50] Speaker 5: disclosed where the body is the parole board can refuse
[19:55] Speaker 5: you parole. But it's still up to the parole board.
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