Adam Matos may face the death penalty after his conviction on Thursday - Representational image REUTERS/Suhaib Salem

A Florida man who admitted to killing his ex-girlfriend in front of their son before killing her parents and her new boyfriend has been found guilty of four killings. Adam Matos may face the death penalty after his conviction on Thursday (16 November), the Daily Mail reports.

According to police reports, the 32-year-old first shot his ex Megan Brown and her father Greg Brown before battering Megan's mother and her new boyfriend, Nicholas Leonard, to death with a hammer at their Hudson home on 28 August, 2014. While confessing to his crime, Matos described how horribly he killed the four. He claimed that a combination of self-defence and "paranoia" drove him to murder them.

Matos also did not show any remorse for leaving his then four-year-old autistic son at the crime scene while he went out to buy a shovel to bury the bodies. The bodies were found stacked four-high on a berm alongside a nearby road. He was arrested on 5 September, 2014 at a Tampa Bay area hotel with his missing son.

In the court room, he described that fateful day of August 2014 as the "worst day of my life, a horrible experience, like a nightmare I couldn't wake up from", the Tampa Bay Times reported.

Born in Philadelphia, Matos lived in Allentown, Pennsylvania, and New York City. He reportedly said he met Megan when he was 18 and she was 16 and after knowing each other for some months, she became pregnant with his child.

But Megan's parents reportedly convinced her to move with them in Hudson and she told Matos she was taking their child. It was then that he decided to make the move.

"I tried to convince her to stay. Tristan was born there, he had friends there, he was going to school, and there were beautiful parks he could go to there. It was a great place to raise our child," Matos had said.

Local media reports said after the killings, the child was adopted by a new family.