A Casper man convicted of intentionally burning down his ex-wife's trailer home will likely spend decades behind bars.

Mark Garrison was sentenced Wednesday in Natrona County District Court to 30 to 35 years in prison after a jury found him guilty on one charge of first degree arson and labeled him as a habitual criminal.

Investigators with Casper Fire-EMS say in late December 2013, a mobile home on Yucca Circle was destroyed by a fire. It was later determined that the fire was intentionally set.

Kathe Garrison was living in the home at the time, but was not there when the fire occurred.

She told investigators that she had been threatened numerous times by her estranged husband, Mark. She said he was going to burn her house down with her in it and kill her.

Before the fire, she had left her dog chained outside. The dog was not there when she returned.

There was no evidence that the dog had broken loose.

An ex-friend of Mark told investigators that earlier on the day of the fire, he saw Mark take a five-gallon gas can and leave.

He testified in court that he saw the gas can the next day, and there wasn't as much gas inside compared to the day before.

The ex-friend said Mark had stated the house was going to burn down anyhow because of bad wiring.

When interviewed by police, Mark said he was in Sweetwater County at the time, but he could not provide times of arrival or an account of his travel. He reportedly said he had reason to believe an electric water heater was improperly wired and that it may have been the cause of the fire.

An investigation later determined that was not the case, and that the fire started in the area of the front porch.

A neighbor testified in court that the fire was on the front porch and going into the trailer.

A security camera from a neighboring house captured footage of the beginning of the fire. Video shows a person walking nearby, then about 20-25 minutes later, the same person walking the other way with a dog, and then about one minute later, the glow of the fire can be seen.

The defense argued that the person in the camera couldn't be identified, because it was dark and snowing at the time, plus a gas can couldn't be seen.

Natrona County prosecutors said in their opening statements that the arson was an act of revenge and also mentioned that Mark pleaded guilty to violating a protection order on four different occasions -- once before and three times after the fire.

Garrison has prior felony convictions of interference with a peace officer in 2002 and escape in 2004, hence the habitual criminal label.

Video from neighbor's security camera played at trial:

The figure can be seen in the upper left-hand corner of the video.

0:00 - 0:10 Person seen walking one direction.

0:11 - 0:22 Person seen walking in other direction with a dog.

0:23 - 0:53  Reflection of fire can be seen in neighbor's vehicle and glow of the fire can be seen to the left.