A 21-year-old St. Paul man linked to a vast spree of violent robberies and carjackings in the Twin Cities has now pleaded guilty to federal charges that also include possessing a stolen handgun.

Ricardo Rydell Walker Jr. entered a guilty plea Tuesday in U.S. District Court that included admitting to stealing a sport-utility vehicle after striking the owner in the head with a handgun June 28, 2022. According to the U.S. Attorney's Office, Walker also admitted to aiding and abetting three other carjackings that took place between 2021 and June of this year — the latter taking place while Walker was in jail on his federal charges.

His convictions carry a maximum 15-year federal prison sentence, but prosecutors have agreed not to request a sentence above 6 1/2 years. U.S. District Judge Katherine Menendez has not yet scheduled a sentencing date.

A message seeking comment has been left with the federal defender representing Walker.

According to court records, Walker was arrested in Maplewood after police and Ramsey County deputies found him and his accomplices sleeping inside a different stolen car than the vehicle he carjacked six days earlier. Walker rammed a nearby squad car after being stirred awake and fled onto public roads before colliding with another vehicle. Police arrested Walker and others following a brief foot chase.

Police also found Walker in possession of a Springfield Armory Hellcat 9mm handgun. After tracing the firearm's serial number, officers discovered that the gun had been reported stolen out of Minneapolis. Walker later told a detective that he bought the handgun from an unknown man in Minneapolis a day before his arrest.

Walker's crime spree netted criminal charges in multiple counties before his case went federal. The June 2022 carjacking followed three violent robberies on June 28 that took place on the Augsburg and University of Minnesota campuses and at a West St. Paul apartment complex. According to charges, Walker and his accomplices pulled off another robbery in West St. Paul earlier on the morning of his eventual arrest.

Walker's penchant for armed robbery began in February 2021, less than two months after he turned 18. Within a year, one criminal complaint read, officers said they were "well-acquainted" with Walker and at least one of his accomplices for "having been involved in numerous robberies/carjackings. [They] were known to display firearms and known to target expensive vehicles."

In December 2021, Walker was civilly committed in Ramsey County District Court as mentally ill and chemically dependent. That put his criminal cases on hold as he entered the Anoka Metro Regional Treatment Center. He was then moved to a less restrictive sober house in St. Paul.

Federal prosecutors filed their charges in January of this year. At that time, Walker was in Department of Human Services custody at the Community Addiction Recovery Enterprise (C.A.R.E.) Program in Fergus Falls and has since been held at the Sherburne County Jail.

Staff writer Paul Walsh contributed to this report.