By Chris Tye

CHICAGO (CBS) — Questions persisted Thursday about what happened in the hours and days prior to the discovery of a body and explosives in a Streeterville high-rise the night before.

The discovery of the explosives in a unit in the high-rise at 240 E. Illinois St. late Wednesday forced the evacuation of several floors and the shutdown of several major roadways – including part of Lake Shore Drive for a time.

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As CBS 2’s Chris Tye reported, the man who lived in the unit and stored those explosives was a genius. He aced the ACT before heading to some of America’s most elite colleges.

He was also described by some as a loner. And he was a singular figure who rattled the neighborhood over the last 24 hours.

Inside a white blast-proof container leaving the apartment in the Illinois Street high-rise late Wednesday was the chemical lead azide (Pb(N3)2) – an explosive agent used to deploy, among other things, airbags.

It belonged to Ted Hilk, 30. What it was doing in possession of the Chicago high-rise resident remained unclear late Thursday.

Police discovered Hilk’s body in his messy seventh-floor apartment. They believe he had been dead for quite a while.

Hilk’s body was discovered overnight Tuesday into Wednesday. Police sources told CBS 2 new information led them to return hours later to discover “multiple explosive devices” in the unit.

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Mayor Lori Lightfoot on Thursday said the devices were not pipe bombs.

Neighbors knew Hilk as a bright tenant.

“Somebody was googling them, and he seems like he had a pretty educated background. So we were more worried, what was he doing, what was he thinking?” a neighbor said.

Nervous neighbors have been left to wonder about motive, but they’re spot-on about that educated background. Hilk scored a perfect 36 on his ACT before attending MIT.

“I have known only a handful who have scored a 36,” said Carolyn Devane, who was Hilk’s high school counselor in suburban Kansas City. “I think his greatest struggle at times might have been the social side of being a teenager and being so off-the-charts gifted.”

Those gifts took Hilk to a career as a researcher at a Chicago tech company here in the loop – until, the company said, he left in 2015.

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What happened on the seventh floor at 240 E. Illinois St. that ended Hilk’s life – and what brought the explosives into the picture – remained key questions late Thursday in an ongoing investigation that now includes the FBI.