NEW FAIRFIELD, Conn. (CBSNewYork)Investigators trying to piece together the circumstances that led to a New Fairfield, Conn. father to unknowingly shoot and kill his own son have been granted access to the teen’s computer to search for clues.

Police said Jeffrey Giuliano, an elementary school teacher, confronted a masked intruder near his home around 1 a.m. on Thursday, Sept. 27, only to later realize the masked man was his 15-year-old son Tyler.

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WCBS 880 Connecticut Bureau Chief Fran Schneidau reports

Jeffrey Giuliano’s sister – the teen’s aunt – lives nearby and called her brother to check on what appeared to be a masked intruder, police said.

The Giulianos have given state police permission to hack into their son’s computer as they search for any information as to why the teen was wearing a mask and why he lunged at his father with a knife.

Jeffery Giuliano opened fire, killing the masked intruder, but did not realize it was his son until police removed the mask.

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Long-time family friend and attorney Gene Zingaro said even with information from Tyler’s computer, the family may never know why their popular, well-adjusted son who was doing well in school lunged at his father with a knife in hand, or why he was apparently trying to break into his aunt’s house.

“We are always going to be speculating as to what he was doing that night,” Zingaro told WCBS 880 Connecticut Bureau Chief Fran Schneidau.

Zingaro earlier this week said the Giulianos are fully cooperating with the investigation.

“I think that state police are going to need to eventually hack into the computer with their computer experts to find out some of these answers,” Zingaro told Schneidau.

Investigators will likely be able to access the teen’s computer by early next week, Zingaro said.

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The medical examiner determined Tyler died from multiple gunshot wounds. No charges have been filed in the case.