A judge has thrown out much of the evidence against the driver of an SUV who’s accused of killing four Iowa motorcyclists in Nebraska last year.

Authorities say 23-year-old Jeser Cisneros-Hernandes of Liberal, Kansas, crossed the center line of a Keith County, Nebraska, highway in July of 2017 and hit two motorcycles head-on. The four who died in the accident were  62-year-old James Matheny and 55-year-old Sheila Matheny of Bedford, Iowa, and 61-year-olds Michael and Jerolyn Weese of Council Bluffs.

The judge ruled this week much of the state’s evidence against Cisneros-Hernandes is inadmissible. The Ogallala police officer reportedly never read him his rights when arresting him for vehicular homicide and reckless driving. The officer’s body-cam footage reportedly shows Cisneros-Hernandes admitting he’d only had one hour of sleep before trying to drive from Montana back to Kansas.