PINELLAS COUNTY, Fla. — A father arrested last July when his infant son died inside a dangerously hot mobile home pleaded guilty to second-degree murder charges Friday.

As part of the plea, William Hendrickson, 26, was sentenced to 25 years in prison.

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At the time of Hendrickson's arrest, Largo Police said he was keeping his 8-month-old son, Billy, and his then-2-year-old daughter, Solara, inside a room in the mobile home he was sharing with his parents.

When officers found Billy's body, they reported the temperature inside the room reached 114 degrees.

Hendrickson was reportedly warned by a Dept. of Children and Families caseworker the day before not to leave the children inside that room. 

Police say Hendrickson locked himself and the two children inside the room after an argument with his mother.

“He doesn’t deserve to ever see the light of day,” said Catherine Rutenbeck, Billy’s maternal grandmother. “But it’s better than going to trial, because that’s a horrible thing to have to go through.”

Billy’s mother, Elizabeth Rutenbeck, said her plan is to now focus on her daughter.

“I’m happy that [Solara]’s happy,” the younger Rutenbeck said. “And I’m going to give her the best life that I can.”

Hendrickson also pleaded guilty to one charge of aggravated child abuse, for which he will serve a 10-year concurrent sentence.