The ex-boyfriend of a woman whose three sons were killed in a house fire has been charged with homicide and arson.

Preston Bonnett, of Wilkes-Barre, is accused of setting the fire at the home in Laflin last week that killed the three brothers. Bonnett, who was arraigned on Monday, vehemently denied the charges and insisted he's innocent.

"They need to do better police work and find out who really did it," Bonnett said.

Erik Dupree, 16, Devon Major, 12, and Ezekiel Major, 7, died in Wednesday's fire. The older boys died of smoke inhalation, while the youngest boy was resuscitated and was flown to Children's Hospital of Philadelphia but died Saturday.

Investigators said Bonnett, who was arraigned on two counts of criminal homicide and three counts of arson, could face another count of criminal homicide after an autopsy is completed on the youngest boy.

Court records show Bonnett is the ex-boyfriend of the children's mother and briefly lived at the home before they had a falling out and she kicked him out.

According to a police affidavit, the children's mother, Susan Major, had gone out on the night of the fire to attend a work-related event, leaving the children at home.

Major told police that a week before the fire she had security cameras, hidden inside Minions characters from the "Despicable Me" movies, installed at her home because she was concerned for her family's safety, according the Citizen's Voice .

Bonnett was previously arrested on an existing warrant for unrelated charges.

The night of the fire, Erik Dupree called 911 about half an hour after his mother had left to report Bonnett was on the back porch, according to the affidavit. Dupree asked police to hurry, saying Bonnett and his mother hadn't been getting along and Bonnett was not supposed to be there, police said.