Ronald Schreffler, a PSU officer from 1972 to 2006, told the court he believed Sandusky acted inappropriately in a shower with an 11-year-old boy in 1998, but that the local prosecutor decided against filing charges, MSNBC reported.
He was one of several campus police officers who hid in the alleged victim's home while the boy's mother confronted Sandusky over the incident.
Scheffler said he heard Sandusky say "I wish I could ask for forgiveness. I know I won't get it from you. I wish I were dead," USA Today reported.
The alleged victim, now 25, also testified about the 1998 incident, telling jurors he recalled feeling uncomfortable while showering with Sandusky. But he also said he couldn't remember anything after Sandusky lifted him up to the shower head to get the shampoo out of his hair, CNN reported.
"I remember seeing his chest hair and thinking, 'This is icky,' " The New York Times reported the victim as saying.
Sandusky faces 52 counts alleging that he abused at least 10 boys over 15 years. Now 68, Sandusky has been under house arrest and has maintained that his contact with children was not sexual, according to CNN.