India, Dec. 15 -- Investigators moved swiftly after gunfire erupted inside Brown University's engineering complex, killing two students and injuring nine others during a final exam review session. Chaos unfolded on campus and a shelter-in-place order was imposed. Authorities began assembling all eyewitness evidence to identify and locate the suspected gunman.

By the early hours of Sunday as per local time, law enforcement had detained a 24-year-old man identified by US media outlets as Benjamin Erickson. Here is how investigators traced him.

Authorities located Erickson using cellphone geo-location technology, which led them to a hotel roughly 15 miles from Brown's Providence campus, according to The US Sun.

FBI Director Kash Patel pos...