ALFRED, Maine (NEWS CENTER) – A man from Biddeford who admitted shooting three people, killing two of them, changed his pleas to guilty.

James Pak shot and killed Derrick Thompson and Alivia Welch after a dispute over parking in December of 2012. Thompson's mother, Susan Johnson, was also shot but survived after pretending to be dead.

"It's something I think about every day, it's not something I think I will ever get past or forget", she said outside the courthouse after Pak changed his pleas.

In December 2012 tensions between Pak and his tenants boiled over in a dispute about parking. Biddeford police were called in, but left when they determined things had calmed down. Moments later Pak went inside the apartment and opened fire killing 19-year old Thompson and 18-year old Welch.

"They were good kids, they were just starting their life, It's not fair", Johnson said.

No one is quite sure why Pak did what he did. A successful businessman who lived a relatively quiet life, he had a stroke in the months leading up to the shootings and was experiencing some mental health issues.

"A myriad of things but a lot of it just unexplainable to even professionals who have examined Mr. Pak", Pak's attorney Joel Vincent said.

Pak will be sentenced next week.