Investigators believe Clardy was involved in prostitution. Palmer was arrested Thursday and told police he had contacted Clardy through backpage.com and met her at a Brooklyn Park home for sex, the newspaper reported.
Palmer told police the two began to "tussle," he choked her until she passed out and hit her in the head with a hammer a number of times, the newspaper said.
Her cause of death was ruled to be multiple blows with foreign object to the back of the head, the Pioneer Press said.
Palmer told investigators he put Clardy in a car, covered the body with blankets, and left the vehicle at a Brooklyn Park apartment complex. The car was discovered 10 days later, on Feb. 21. Clardy's parents had reported her missing to police Feb. 11.