On April 24th, 2017, nearly two years after Mariam Rashidi was killed, jurors began hearing evidence against Mitchell.

Joshua Mitchell was a 20-year-old who didn't really do that much other than commit petty crimes, and one of the things that he and his friends liked to do was walk up and down the street and look for vehicles that were unlocked, and oftentimes they would steal things from inside the vehicle.

A few days before this incident, so on June 1st, 2015, uh, Joshua Mitchell and some friends were doing this very thing in Airdrie, and they had come across a truck that was unlocked and that, uh, had its keys in it.

The truck was still hooked up to a trailer with a boat on it.

And so Mitchell stole the 2006 Ford F350 truck from outside of its owner's residence and the boat, and, uh, they later abandoned the boat, uh, but used the truck for the next few days, primarily for joyriding, and then every day or two, they would steal fuel, uh, to keep the truck running.

We immigrated to live, not to die."

In Canada, we're not allowed to talk to jurors, so we never know why they decide what they decide.

I think the fact that this was a fuel theft, that it was somewhat of a lark, and that he was really quite a, a young kid, would have played heavily in the minds of the jury.

However, the prosecution told jurors Maryam's death was no accident, and said Mitchell had the power of life and death over her, and he chose death.

But the jury had a very difficult decision.

The jury could easily find that Joshua Mitchell, by driving the way he did, intended to cause bodily harm, knowing that death was a likely result, and was reckless as to whether or not death ensued, because he was clearly going to get her off the vehicle no matter what the consequences.

Conversely, the jury also had a compelling argument that he wasn't really trying to hurt her.

He just wanted her to get off the vehicle.

And that's what they would have struggled with in the jury room, the Crown's theory of intent and the defense's theory that this was an unintentional event.

And I think because he was still a young man and really looked like a young man in the prisoner's dock, that would have weighed heavily on the jury.

Mitchell appealed his sentence with the help of veteran defense lawyer Balfour Der.

Hack told me the theory he presented to the court was the same for both cases, in which a prolific offender's desire for money and drugs fueled a violent crime spree that left one man with a brain injury, and a young woman dead.

I've prosecuted lots of murderers and lots of other crimes that have resulted in far too many deaths, and what stood out about this case is the randomness of some violent crime, where it isn't a person you have a grudge against.

It isn't someone who has wronged you.

It is just someone who is a means to an end.

And so this case really struck me as indicating how random things can be in our lives.

So after the ATM robbery, where he gets $30 from, uh, the victim's wallet and the car, he goes back to his sister's place, tells them that he has this car, which they ask him to park somewhere else, and he's got $30.

So he then goes out to buy some crack cocaine, comes back, $30 of crack cocaine doesn't last long.

This time, he was accused of the first-degree murder of Tara McDonald.

Longtime Alberta prosecutor Jonathan Hack says despite what people might assume, from his experience, a hammer is not usually a weapon of choice.

If a weapon is going to be used, it would typically be a knife or a gun.

Hammers are convenient, though, because they're not illegal.

It's not illegal to walk down the street possessing a hammer, and it's a very effective silent weapon.

The hammer also stood out to investigators because there had been another similar violent attack just two hours before Tara's murder, down the street from the Subway.

He was quite seriously injured.

He also suffered a depressed skull fracture, and he had several additional hammer hits.