Police say a 13-year-old central Iowa boy found dead days after he left his home in freezing temperatures died after falling from a communications tower he had climbed. The Marshalltown Police Department said Wednesday in a news release that an autopsy showed Corey Brown died of a significant head injury. An investigation showed the boy had climbed over a secure fence to enter the tower site, climbed onto the tower and fell from an undetermined distance, causing the head injury. Corey was last seen alive at his home around 11:15 p.m. Jan. 22, when surveillance video showed the boy leaving the house. His body was found five days later on Sunday. Police say the investigation remains active, and there is no evidence of criminal activity related to the boy’s death.