Which Prime Suspect show was this?

I am pretty sure it is one of the Helen Mirren Prime Suspect "movies". I saw it on the hotel tellie when I was in England a few years ago. I scanned through clips from them and have read their descriptions but I can't find which episode it was. None of them look right. It may not have been a Prime Suspect episode. This is what I remember. But it may have other shows mixed in:
A 20 something guy kills a teen girl. I think in a mobile home. His mother is shielding him. Ms Mirren is interviewing the mother and tries to show her pictures of the dead girl. The mother refuses to look at them so Helen describes them to her. Later, a black man is arrested. He has mental problems and hangs himself in jail from terror. His older sister tried to get him out of lockup in time.

I think it must have been this episode of Prime Suspect.

(From Wikipedia):
"Operation Nadine: Part 2"
"....inconsistencies between his story and the evidence cause Tennison to believe the murderer is still at large. While in police custody, Tony hangs himself in his cell, leading to an inquiry..."

The actor playing the character who hangs himself is Fraser James, a British actor of African Caribbean heritage.