19x02: Why did the DJ die?

*Spoilers*

At the end of "After the Fall", we discover Lydia Hamilton (the lawyer) hired the bodybuilder-turned hitman Carmichael (who has impressive forensic abilities and a hairy chest) to kill both the DJ and the old retired nurse, amongst others.

It's explained that as Lydia felt she was so caught up in the legal case that the nurse was highly involved with in the last few months of her life (arguing that a company caused pollution resulting in higher levels of cancer) that she didn't pay enough attention to her daughter who committed suicide.

However, it isn't explained why she hired Carmichael to kill the DJ, who was the first body discovered in the two-parter. We know that Carmichael befriended him in the cancer support group but it was clear that the DJ was not involved in the legal case and he didn't know the nurse. The only apparent link between the two was the priest (who was the nurse's son).

Carmichael is a hired killer, so he was only going to kill people he was paid to kill. He even tapes the conversation between himself and Lydia where he says "If I'm going to kill them, I want the money upfront". Lydia was killing those that she blamed for her family falling apart around her (the DI who suppressed Suzi Banks' confession that Tony was innocent, the expert witness who failed to convince the jury of her husband's innocence, and as previously mentioned the nurse at the centre of the legal case that caused her to become estranged from her daughter) so what was the motivation for killing the DJ? He seems to have no link to any of this.