After receiving the tape from Franklin Bedford, two detectives and two district attorney watch the video. Franklin didn't want the tape to get out to protect Alison Conway, because she's like a sister to him. If Franklin didn't killed Tagg, then somebody framed Franklin, someone who had access to the weight room and Franklin's locker, as said by Jack McCoy. He thought that he and Abbie Carmichael needed to have another talk with Alison. I don't know what will happen if I choose No.
During the interview with Alison, Abbie and Jack said that they had some reason that Tagg sent the tape to Harrison, and suddenly, Alison remembered that that explained the attack. She also said that 'They' never told her who attacked Tagg. For Tagg's Harrison's murder, Abbie and Jack found something unfit with the timeline. Like Jack said: Something's wrong with this picture, and like Jackie Chan in JCS said: Something's Wrong Here :v .
Later, Abbie interviewed Mrs. Vanderhoek. We can find that her full name is Tricia Vanderhoek. As I thought, Franklin Bedford was framed. So, can you guess who had access to the weight room and who framed Franklin Bedford (remember, these questions direct toward one person)?