When a person is missing and presumed dead, neither family nor investigators can have closure until his or her body is recovered.
With that in mind, the RCMP's Historical Case Unit in Saskatchewan conducts an annual river search for missing persons.
But Dr. Ernest Walker, a forensic anthropologist with the Major Crimes Unit in Saskatchewan, says the team noticed that sometimes bodies go into the river system and are never found. So they suggested putting something in the water to see where it goes.
"What we're looking for is a predictive model because we know bodies can travel a long way," says Walker. "We have to get a grip on all the factors like what time of year it is, where a body goes in, how they go in, the temperature and the flow rate."
Tracking in the river
In September 2013, Walker and his team implanted a tracking device on a pig carcass and released it into the North Saskatchewan River near the small city of North Battleford.
"We've pulled cadavers out of the river in various locations and noticed they've sometimes travelled several kilometres before being discovered," says Cpl. Tyler Hadland of the Historical Cases Unit.
As soon as they put the pig into the river, it immediately started to float away. But it didn't get very far before it got stuck on a sandbar. When the team went back to collect the pig a few days later, they couldn't find the animal or the transponder. Hadland says they believe it went to rest close to the shore and animals devoured it, dragging it to a different location.
"I think the moral of the story is that just because a body goes into the water, it doesn't necessarily mean it stays in the water," says Walker. "And that's something we hadn't contemplated."
They tried again in February 2014 in the South Saskatchewan River in Saskatoon. Because of the temperature of the water, the pig carcass sank right to the bottom of the river and stayed there until the water warmed up in the spring.
The body then floated down the river and eventually came to rest on a riverbank. But by the time they arrived to pick it up, only the tracking device was left.
Gathering data
The Historical Case Unit's Sgt. Kenneth Palen says that while this type of hands-on research isn't typically the work of investigative units, it gathers information to potentially solve current or cold cases. And it could help police in future cases narrow down search areas when a person goes into a body of water.
Hadland adds that having police officers participate in this research is an advantage because they're typically involved in a case from the beginning and may have access to information independent researchers wouldn't.
Early on, the team also got the Saskatchewan Water Security Agency involved.
Iain Phillips, a researcher with the provincial body, provides support in tracking the pigs. Once they recover a carcass, he plans to study the aquatic insects it attracts. His research will help develop forensic tools for future investigations.
"By studying the life stages of insects that have colonized the body, we can determine how long it's been since the body was submerged," says Phillips. "A lot of times we'll already know where a missing person originated from. But if we don't, this could provide us that evidence."
In the future, the team plans to launch a few pigs at once — increasing the likelihood of recovering a carcass they can actually study — to test whether two bodies launched under the same circumstances would take the same paths. Palen adds the ultimate goal of all this research is to find closure for those who need it.
"We know it's such a hard thing for the family not knowing where their loved ones are. They know they went into the water, but why can't they be found, why aren't the police doing anything?" says Palen. "But with this and the river searches, we can send updates to the family to show them that their case is still open and that we're looking for their loved ones."