05/11/2015 07:40 EDT | Updated 05/11/2016 05:59 EDT

Randy Janzen's family: Police seeking anyone who had contact in past 3 weeks

Homicide investigators want to trace the Janzen family's steps leading up to a triple homicide that rocked a Fraser Valley community in B.C. last week. 

Randy Janzen allegedly wrote a confession on Facebook that he killed his 19-year-old daughter Emily because she was suffering from migraines and depression.

He's also believed to have killed his wife Laurel and sister Shelley. Janzen died Thursday night after a standoff with police in the Rosedale Popkum area east of Chilliwack.

"At this point, our priority is to speak with anybody who had been in contact with the Janzen family in a three-week period leading up to the incident on May 7," says Sgt. Stephanie Ashton.

Police believe the victims of the triple homicide under investigation are members of the Janzen family, although the B.C. Coroners Service has not yet confirmed their identities.

"Three badly burnt bodies have been located and this is consistent with what was posted on Facebook by Randy Janzen," Ashton added.

Apparent confession posted to Facebook

​The Facebook post from the man identified as Randy Janzen contains an apparent confession to the murders.

"I took a gun and shot her in the head and now she is migraine-free and floating in the clouds on a sunny afternoon, her long beautiful brown hair flowing in the breeze, a true angel," the post says.

"Now my family is pain free and in heaven," it concludes. "I have great remorse for my actions and feel like the dirt that I am."

The post says the man shot his wife "because a mother should never have to hear the news her baby has died" and, "a couple of days later," killed his sister "because I did not want her to have to live with this shame I have caused all alone."

The post is signed "Love Daddio."

The CBC cannot confirm that Janzen actually wrote the post.