Medford police say a tipster coming into the station with evidence on a camera was what led to the arrest of 55-year Gregory Looper, who was sentenced to 25 years in prison Wednesday for child sex abuse charges. The informant left no other information at the time. Within 24 hours of receiving the tip, detectives were able to gather enough information to get a search warrant. He was indicted in August and agreed to a plea bargain. He pleaded guilty to four Measure 11 sex crimes.