(KRON) -- The Alameda County Sheriff's Office is searching for a missing man. Robert Contreras, 38, was last seen leaving his Castro Valley home on June 28. The sheriff's department believes he could be in Castro Valley, San Leandro or Hayward. He is described as 6-foot-3, 150 pounds with brown eyes and a bald head or a buzzcut. Juveniles arrested in car linked to three Vallejo armed robberies Contreras is known to go to the Greenhouse Marketplace, a shopping center located at 699 Lewelling Blvd. in San Leandro. He does not have a cell phone and does not typically use public transportation, police said. ACSO does not know what clothes he is wearing. "We are all concerned about Robert's safety and ask for your help bringing him home," ACSO said. Anyone who sees Contreras or has information is asked to call ACSO at (510) 667-7721.