Family members and police are asking for the public's help in finding a 28-year-old Riverside man who mysteriously went missing last month. Samuel Joel Galvan was last seen Sept 11., according to Riverside Police Department investigators, who consider his disappearance to be suspicious. Some additional details about the the case could not be immediately disclosed, said Lt. Frank Assumma. Galvan left his home in the city's Orangecrest neighborhood, where he lives with his mother and sister, at about 2 a.m. and did not return. About a week later, a notice arrived in the mail stating that the man's car had been impounded in Corona. "I noticed that he left his light on, and usually when he goes out for whatever -- he's getting snacks or something -- he usually doesn't leave the light on," said sister Daniela Galvan. "All his stuff was still there and his phone was off. His phone's usually always on." In a statement issued Sept. 28, police said the man's cellphone "appears to be off and his location is unable to be tracked." Authorities said his car was accounted for but it was unknown if he was possibly traveling in another vehicle. According to flyers distributed by Galvan's family, he was driving a charcoal-gray 2006 two-door BMW convertible. "The car was found stolen," the flyer states. "Foul play is suspected." Galvan is described as white, 5 feet 10 inches tall, weighing 210 pounds. In a photo released by police, he has brown eyes, dark hair, a goatee and is wearing black glasses with rectangular frames. "I miss my son very much," his mother, Cynthia Galvan, said in an emotional interview. "I just want him home. We love him very much and he's loved by so many people." Anyone with information about Samuel Galvan's whereabouts is asked to call the Riverside Police Department at (951) 354-2007.