CTV’s investigative news program W5 is set to revisit a horrifying multiple murder-suicide in Alberta, revealing chilling new clues into the mindset of the killer.

Airing Saturday, Road to Murder, is an hour-long documentary that re-examines the Dec. 15, 2011 killings of Lethbridge woman Tabitha Stepple, 21, and promising baseball players Mitch MacLean, 20 and Tanner Craswell, 22, of Prince Edward Island by Stepple’s ex-boyfriend Derek Jensen, 21, who also took his own life.

Hosted by longtime CTV news anchor Lloyd Robertson, the program features a lengthy interview with Shayna Conway, who was Craswell’s girlfriend and the sole survivor of the tragedy despite being shot four times.

It also reveals, for the first time, a series of text messages sent from the killer to Stepple in the days leading up the murders.

“They were on Tabitha’s phone,” said Larry Day of Calgary’s Pyramid Productions, who produced and directed the episode for CTV. “The family had it but they had never looked at them. They felt it would be too painful. You can imagine it took us some time to win the trust of the family to go over them together.”

Day has been investigating the case for a year. He flew Conway, members of her family and members of the MacLean family in from Prince Edward Island in November to conduct the interviews with Robertson in Calgary. Stepple’s parents, friends of the victims and police officials are also interviewed for the documentary.

“I just wanted people to know it is basically a life sentence for the survivors,” Day said. “For Shayna and the families, they live with it forever. It’s an amazing cost.”

Jensen shot MacLean, Craswell, Stepple and Conway multiple times at the side of Highway 2 between Lethbridge and Calgary, not far from Claresholm. The four were driving to the Calgary Airport so MacLean and Craswell could fly home to Prince Edward Island for Christmas. Jensen followed them and, on a dark stretch of highway, rammed the car from behind.

It followed an incident in Lethbridge, when Jensen confronted Stepple at the Blarney Stone pub, who was there with friends to celebrate Tanner Craswell’s 22nd birthday. Both Craswell and MacLean were in town to play with the Lethbridge Bulls, a summer collegiate baseball team and to attend the Prairie Baseball Academy. Craswell played shortstop and MacLean played second base.

Jensen came from a Mormon family and grew up in Lethbridge. He was training to be a paramedic. He had also shown a dark, possessive side leading up to the killings in his dealings with Stepple.

“We also wanted to answer Lloyd’s question in the piece, which is why,” says Day, who is also president of Pyramid Productions. “Why would a young man who people described as being such a great guy and great friend do this? Why did he snap? Then we ask the question: did he snap or was it premeditated?”

The episode also features a lengthy interview with Conway, who describes the shooting in detail while discussing her battles to overcome both her injuries and survivor’s guilt.