The man suspected of shooting dead four people midtown Manhattan last month had years earlier threatened to kill himself as he dealt with depression and concussion symptoms, according to a phone call his mother made to police.

Terrifying scenes in Midtown Manhattan showed office workers running for their lives with their hands in the air. The surveillance image shows the suspect, identified as 27-year-old Shane Tamura, entering the skyscraper with an M-4 assault rifle at his side.