Story highlights Tyler Hadley killed parents in 2011, then held party, authorities say

Hadley, 17 at time of killings, could be sentenced to life in prison

Hadley had previously pleaded not guilty, was weeks from going to trial

A Florida man accused of killing his parents with a hammer when he was 17 and then hosting a party pleaded no contest Wednesday to two counts of first-degree murder with a weapon.

The move by Tyler Hadley, who previously pleaded not guilty, came less than a month before he was to stand trial for the July 2011 deaths of Blake and Mary Jo Hadley.

Hadley could be sentenced, at a maximum, to life in prison without parole. A judge in Florida's St. Lucie County will hold a mitigation hearing to determine whether Hadley's youth or other factors should lead to a lesser sentence.

A prosecutor told Hadley that he intends to detail the state's entire case during that hearing, and that because of this, Hadley shouldn't think that he's sparing his family the public airing of evidence in court by pleading no contest.

St. Lucie Circuit Judge Robert Makemson then asked Hadley whether he wanted to change his mind about the plea.

"No, sir," Hadley said.

Authorities said Hadley beat his parents near and in the master bedroom of their Port St. Lucie home on July 16, 2011.

In Wednesday's plea hearing, the prosecution said evidence shows that Hadley had been using drugs and was upset about his parents' plans to put him into a "day treatment program."

After killing his parents, Hadley used "books, files, towels, anything that he could find inside the home to cover the bodies" in the bedroom, Port St. Lucie police spokesman Tom Nichols said at the time.

Before the killings, Hadley had posted on Facebook an invitation to a party at his home. Hours after the slayings, between 40 and 60 people showed up for the party, police said.

Authorities received an anonymous tip and found the bodies while conducting a welfare check at the house early the next morning.

Police said Hadley had dropped out of high school and had taken classes at Indian River State College.