Officers intially responded to a home in the 11600 block of Beacon Avenue South at about 10:30 p.m. after receiving a 911 call. The caller said the 29-year-old male suspect was masturbating onto an 11-year-old girl who is his stepdaughter, said Detective Mark Jamieson of the Seattle police.
When the suspect was confronted, he fled the house on foot.
Officers arrived quickly and surrounded the area as K-9 team arrived and began searching for the suspect.
After about 20 minutes, the suspect was tracked down and arrested without incident in the 11800 block of 54th Avenue South.
He was positively identified by witnesses and booked into the King County Jail for investigation of child molestation. The case remains under investigation.