Opening statements started Friday in the case of a Pasco County man accused of killing four people. 

Adam Matos is accused of killing his ex-girlfriend, her new boyfriend, and her parents back in 2014. Prosecutors believe jealousy may have been the motive for the murders.

His team defense team Friday declined to deliver an opening statement. The prosecution painted a gruesome picture that unfolded when Matos' former girlfriend started a new job and new relationship in a new town.

The 32-year-old is accused of killing Megan Brown, Nicholas Leonard, and both of Brown's parents in Hudson.

"This defendant, Adam Matos, threatened to kill the mother of his child, Megan Brown, and then later that day, he made good on his threat, came back and killed her, her parents Greg and Margaret and her new boyfriend Nicholas Leonard," prosecutor Bryan Sarabia said in court.

The prosecution said Megan Brown was shot through the eye and that her mother was found beaten to death with a hammer. Leonard was beaten so badly that his skull was caved in, according to the prosecution, who said Matos spent hours if not days trying to clean everything up.

Matos also used Brown's credit card to buy a video game system, pizza and a shovel, prosecutors said, adding that he sold the family's puppies and allowed the buyers inside the home while the bodies were still inside.

After four full days of questioning dozens of potential jurors, the final 12 were sworn in Thursday for a trial that is expected to last several weeks. What made the jury process particularly difficult was this being a death penalty case.

Under Florida law, any death penalty sentence must be approved unanimously by the jury. 

Each potential juror was asked if they could, under any potential circumstance, consider capital punishment. 

In court throughout the week, Matos sat next to his attorneys, clean-shaven and wearing a suit, looking very different than he did back in 2014 when he was arrested and charged with the brutal murders. 

Matos' attorneys say he's maintained his innocence all along.