A man turned himself over to police Monday morning and was being questioned about the attack, said Officer Nicole Trainor, a police spokeswoman. Charges are pending.



The 25-year-old woman left the train and was walking on the 1400 block of West Jarvis when the man grabbed her from behind, police said.



The man displayed a handgun and forced the woman to a secluded area, where he robbed and sexually assaulted her, police said.



The man was described as black with a dark complexion, 25 to 35 years old, about 5 feet 8 and 165 to 200 pounds, police said.



He was wearing a black winter jacket and black knit hat, police said.



Anyone with information is asked to call Area North detectives at 312-744-8261, police said. Tips can be submitted to Tipsoft.com.