This is part of my ongoing series on Canadian Mass Murders.

Jealousy is one of humanity’s ugliest emotions.  It renders its owner incapable of responding rationally to any situation involving the object of their jealousy.

When a rational person sees their former romantic partner enjoying themselves in the company of another, they may feel anything from sadness to joy, but what they don’t feel is murderous rage.

Not so for 21-year-old Derek Jensen from Lethbridge, Alberta.

When Derek Jensen stumbled across Tabitha Stepple, his ex-girlfriend, out with a friend and two minor league baseball players at a Lethbridge pub on the night of December 14, 2011, the final thread holding his sanity together broke.

A few hours later three young people would be dead on the side of an Alberta highway. Two others would cling to life until help arrived. One of them would die on the way to hospital. The other would make it, only to fight for her life while surgeons removed three bullets from her body and repaired the damage.

All because one jealous young man couldn’t stand seeing his ex-girlfriend talking to another.

Chance Encounter Leads to Confrontation

On December 14, 2011, Derek Jensen went out to a Lethbridge pub with friends.

By chance, Tabitha Stepple, Jensen’s ex-girlfriend, was at the same pub with co-worker Shayna Conway, her boyfriend, baseball player Tanner Craswell and his teammate Mitch MacLean.

Mitch MacLean and Tanner Craswell were scheduled to fly home to Prince Edward Island for Christmas but, instead of accepting a ride with their coach earlier that day, they opted to stay longer so Tanner could celebrate his 22nd birthday with Shayna.

Jensen got into an altercation with Tabitha, during which he knocked the young woman out of her chair onto the floor. She and her friends left the pub shortly after that.

Enraged that his ex-girlfriend was spending time with some other guy, Derek Jensen left the pub and attempted to follow Tabitha Stepple, Shayna Conway, Mitch MacLean and Tanner Craswell.

As he drove around searching for them, Jensen called Tabitha’s cell phone repeatedly and, according to witnesses, screamed at her.

“This night’s not going to end well for you. I hope you know that.”

Then he saw their vehicle at a convenience store in Claresholm. They didn’t notice Jensen following as they left for the long drive to Calgary International Airport.

Threat Turns to Murder

At approximately 3:30 a.m. on December 15, 2011, Derek Jensen rammed his car into the back of the SUV with the four young people inside on Highway 2 just north of Claresholm, Alberta.

When Shayna Conway pulled over to deal with whoever rammed their vehicle, Derek Jensen jumped out of his car, shot Shayna Conway three times on the side of the road before shooting the other three inside the vehicle.

The primary focus of his murderous rage was Tabitha Stepple, the murderer’s ex-girlfriend. Unfortunately, 21-year-old Shayna Conway simply got in the way.

Thinking everyone was dead, Derek Jensen killed himself as Shayna Conway watched.

Impossible Murder to Prevent

Derek Jenson was not “known to police.”

He had no criminal record.

He had no history of domestic abuse with his former live-in partner, Tabitha Stepple, despite a relationship that friends called volatile.

Tabitha’s friends recounted stories of his controlling and abusive nature for the media, but none of those incidents were reported to either the RCMP or Lethbridge Police.

In short, there was nothing in his past to give police any indication he was capable of such a murderous rampage.

Derek Jensen was an avid hunter and licensed gun owner who legally possessed four firearms, including the H & K 9mm handgun he used to wound Shayla Conway, murder Tabitha Stepple, Mitch MacLean and Tanner Craswell and end his own life.

Inside his vehicle were a loaded 12-gauge shotgun and a loaded Winchester rifle, evidence of his premeditation for the murders.

A fourth firearm and ammunition were found at his home during a police search.

Report Violent Domestic Situations to Police

Police can only remove firearms from the possession of a domestic abuser if they’re notified.

If you or someone who care about is involved in an abusive relationship, please ask for help. There is no reason on earth why you should stay with someone who does not treat you with love and respect.

Get out while you still can, because the list of women who stayed too long is, well, far too long.