As federal kidnapping charges move forward against four Uber drivers accused of sexually assaulting passengers across the Houston area, court records are beginning to reveal details about each case.

William Brock, 83, was convicted of three counts of murder, one count of felonious assault, and one count of kidnapping on Jan. 14.

William J. Brock fatally shot the driver after wrongly assuming she was in on a plot to get $12,000 in supposed bond money for a relative, authorities said.

This week’s revelation by the U.S. Attorney’s Office for the Southern District of Texas, implicating four rideshare drivers in separate kidnapping and sexual assault incidents, has naturally raised safety concerns for passengers.

The men were targeted under Operation Lighthouse, an initiative led by federal and local law enforcement agencies to charge rideshare drivers accused of sexually assaulting female riders.