Following an apparent ambush that killed two Bristol police officers and sent a third to the hospital, law enforcement experts say the investigation will focus on potential early warning signs – and how much information the officers had responding to the call.

Sgt. Dustin DeMonte and Officer Alex Hamzy both died in the shooting around 10:45 p.m. Wednesday. Officer Alec Iurato was injured but released from St. Francis Hospital Thursday afternoon. Connecticut State Police say the suspect, Nicholas Brutcher, may have used a phony 911 call to lure the officers to his home. Brutcher also died in the exchange.

"It's very hard when someone is intent on targeting a police officer,” said Gary MacNamara, a former Fairfield police chief who now serves as Sacred Heart University’s public safety director.

MacNamara said investigators will look at possible warning signs, including numerous pictures and videos Brutcher posted to social media prominently featuring guns. Detectives will also look at whether officers had enough information heading to the call.

"We're going to want to find out everything that happened prior to the call for service,” said MacNamara. “What happened prior to, at that residence. What information was provided to the officers."

After a similar attack in Newington 18 years ago, the state developed a tool for responding officers. The Connecticut Information Sharing System (https://portal.ct.gov/CJIS/Content/Applications/Connecticut-Information-Sharing-System---CISS) includes 52 databases, instantly searching DMV records, lists of wanted people and warrants, protective orders and prison records. Most importantly, it tells officers what guns are registered at an address.

Most officers can access CISS in their patrol cars. Emergency dispatchers can search it too.

"Whether or not the officers in this case had the ability to that, we don't know,” said Mike Lawlor, a former criminal justice adviser to Gov. Dannel Malloy who now teaches at the University of New Haven. “But the goal is that officers should have piece of information about the situation they're responding to."

But MacNamara said a database can only reveal so much, especially if no one raised red flags to authorities.

"We have to do all we can to prevent these from happening in the first place,” he said. “We always have to do a better job of identifying individuals that should be held accountable prior to an incident happening."

According to state police, Brutcher used an AR-15 style rifle. Connecticut banned such weapons after the Sandy Hook school shooting, but they’re still legal if you owned it before 2013. Investigators are looking at how Brutcher obtained that weapon -- and whether it was legally registered. MacNamara said patrol officers always wear bulletproof vests, but assault rifles can pierce them. He said heavier vests are usually reserved for SWAT situations.