Investigators have uncovered new details about the individual who opened fire at a Dallas Immigration and Customs Enforcement (ICE) facility on Wednesday morning, killing two detainees and injuring a third before taking his own life. The suspect, identified as 29-year-old Joshua Jahn, was found with a map depicting radioactive fallout in the United States affixed to his vehicle.

Authorities reported that a bullet recovered at the scene bore the words “Anti-ICE” scrawled on it. A tattered map, reportedly attached to Jahn’s blue Toyota Corolla, displayed areas of the U.S. where radioactive fallout from nuclear detonations had allegedly occurred since 1951. The text on the map stated: “Radioactive fallout from nuclear detonations have passed over these areas more than 2x since 1951.” The image appeared to be based on data compiled by researcher Richard Miller, highlighting regions affected by nuclear testing in Nevada between 1951 and 1962.

Jahn targeted the Dallas ICE office from a rooftop, firing on a van carrying detainees awaiting processing. He died by suicide after the attack. Records indicate Jahn’s parents reside in Fairview, Collin County, where FBI agents were seen investigating their home following the incident. Local authorities confirmed that Fairview police are assisting with the probe.

No prior violent criminal history was found for Jahn, though he was arrested in 2015 for marijuana possession in Collin County. Investigators continue to examine his motives and connections to anti-ICE sentiments.