Jurors at the Jeremy Steinke murder trial heard the 25-year-old accused killer, in his own words, tell an undercover officer about the crime.

Jurors spent much of Tuesday listening to a tape that the prosecution says was recorded by an undercover police officer who was with Steinke as he was being transferred from Medicine Hat to Calgary days after the murders.

On the tape, Steinke describes the last moments of his girlfriend's father. "The last thing I really remember was him and after him attempting to stab me [expletive] him laying on the ground asking me why and I said 'cause you treat your daughter like [expletive], she wanted it this way,' and [expletive] and that was it and then I went upstairs and I watched my girlfriend cut her brother's throat. [indiscernible] it didn't bother her at all either, she didn't cry or anything in fact the next day when we were on the road [expletive] she was laughing about it. She's got a few screws loose too," said Steinke.

During the two-hour recording Steinke repeatedly referred to his girlfriend as his soul mate and says the two were engaged.

At one point, he said he even tried to talk her out of the murders but claims she was intent on going forward with the plan. "I never thought that I'd actually kill anybody but when - once I found my - my soul mate, my true love, I just for some reason, I was willing to do anything for her," said Steinke.

Steinke went on to tell the undercover officer that he was drunk and high on cocaine the night of the murders. He also said he blacked out several times and cannot remember exactly what happened.

He talked about his plans for the future with his girlfriend - who was 12-years-old at the time of the murders - and is hoping to once again be together when they are released.

In April 2006, Steinke's girlfriend's parents and eight-year-old brother were murdered in their Medicine Hat home.