A 21-year-old student shot dead by campus police had called 911 to report an armed person matching his description prior to the incident, officers said.
Scout Schultz was said to be advancing on police with a knife when he was shot on Saturday, the Georgia Bureau of Investigation (GBI) said.
A vigil was held on Monday which descended into violent protests, with videos posted online showing a police car burning in the street.
Investigators have determined that Mr Schultz was the one who called Georgia Tech police to report a suspicious person on campus, GBI spokeswoman Nelly Miles said in a statement on Monday.
"In the call, Shultz describes the person as a white male, with long blonde hair, white T-shirt and blue jeans who is possibly intoxicated, holding a knife and possibly armed with a gun on his hip," Ms Miles said, adding that three suicide notes were found in Mr Schultz's room.
Investigators recovered a multi-purpose tool that included a knife at the scene but didn't find any guns, Ms Miles said.
Chris Stewart, an attorney for Mr Schultz's parents said the GBI confirmed to him that the blade on the tool was not out.
Flanked by Mr Schultz's parents earlier on Monday, Mr Stewart said the officer who shot Mr Schultz overreacted.
Mr Schultz was having a breakdown and was suicidal but if the officer had used non-lethal force rather than shooting, he could have received treatment and gotten better, Mr Stewart said.
"The mentally ill are looking for a way out when they're having a full breakdown, and there's no way you should be able to use a police officer to take your life when that person isn't threatened," he said.
Authorities have not identified the officer who shot Mr Schultz nor have they released the audio of the 911 call, which came in around 11.17 pm on Saturday, according to the GBI.
Georgia Tech has refused to release personnel or disciplinary reports involving the officers, saying such information is exempt from Georgia's open records law.
Mr Schultz was president of Pride Alliance at Georgia Tech and the fourth-year computer engineering student used the name Scout, rather than the given name Scott, and preferred the pronouns "they" and "them" rather than "he" or "him."
"I'm bisexual, nonbinary and intersex," Mr Schultz wrote in a Pride Alliance profile.