Osvaldo Rivera, of Camden, was found guilty Friday of felony murder and numerous other charges by a jury that reached its verdict after deliberating for less than three hours. He faces life in prison when he's sentenced Oct. 23.
Authorities said Rivera, 33, broke into the children's home in September 2012 while they were asleep and their mother was in the hospital recovering from a surgical procedure. Rivera was trying to assault a 12-year-old girl when her little brother intervened to protect her, investigators said.
Rivera slashed the children's throats, authorities said. The girl ran to a neighbor's house for help.
Two other girls, ages 9 and 14, were inside the home but weren't injured.
At the time of Rivera's arrest, there was speculation that he had been smoking "wet," or marijuana laced with PCP. But authorities said that has never been confirmed, and the issue wasn't raised during the trial.
Claims were made at trial that Rivera was drunk when the assault occurred, but prosecutors said there was no evidence Rivera had consumed alcohol around the time of the attacks.
They also noted his winding escape route, which they said showed a clear awareness of having committed an offense, and his physical actions - such as leaping fences - that demonstrated balance and coordination unlikely in a person so intoxicated they would be unaware of their actions.
Besides the felony murder count, Rivera was also found guilty of murder, attempted murder, aggravated sexual assault, burglary, making terroristic threats, weapons offenses and two counts of child endangerment.