 We don't know his opinions or affiliations. I'm standing in front of the accused shooter's home, surrounded by police tape. Authorities believe he acted alone. Fox's Jonathan Serian, Bethel Park, Pennsylvania. 20-year-old Thomas Matthew Crooks was not on law enforcement's radar. No social media rants that they could find. Investigators have yet to determine a motive. They're unaware of any ideology he might have had.