SIOUX CITY, Iowa (AP) — Two Sioux City brothers have been sentenced to federal prison for the armed robbery of two drug dealers.

Officials say 23-year-old Jamal Dean was sentenced Thursday to life in prison after being found guilty of several convictions, including carjacking and two counts of robbery, among other convictions. His 25-year-old brother, Levon Dean Jr., was sentenced to more than 30 years.

According to a release, Jamal Dean was already serving a 25-year prison sentence after pleading guilty to attempted murder in the April 2013 shooting of a Sioux City police officer.

The release says the two traveled together from Nebraska to Iowa and conspired to rob local drug dealers on two occasions in April 2013. After each attack, the brothers returned to Nebraska.