I started watching Law and Order CI late in the season and now I'm hooked on it. I saw an episode where?

Detective Robert Goren (Vincent D'Onofrio) had found a serial killer who had picture diaries of the women that he murdered. Det. Robert saw his mothers picture in one of the diaries, and asked his mother how the killer had her picture. The episode ended with the possability that this serial killer might have been Det. Robert's biological father. If there's anyone out there that saw the next episode, was the killer his father?