A white Muslim, Mershaw was convicted of beating a Jewish man who'd shot his friend. He constantly butted heads with the Muslim Imam of Oz, Kareem Said, and was verile toward any who insulted the word of Allah. He hinted to another Muslim, Zahir Arif, that they would be better off with Said dead. One morning, Mershaw awoke to find Said having a heart attack. Instead of helping, Mershaw walked away and left him to die.
[Episode 06: "To Your Health"]

With Said in critical condition at the hospital, Mershaw told the other Muslims that Said had told him to organize them for a great holy war. But when Said returned, he shunned Mershaw from them. Mershaw tried to get Simon Adebisi to kill Said, but Adebisi wouldn't even look at Mershaw. So Husseini went to Unit Manager McManus and Warden Glynn, claiming that Said and the Muslims were stockpiling weapons. Emerald City was searched, and the Muslims were the only ones that did not have weapons. The prisoners' extra freedoms were removed, and Mershaw transferred to Gen Pop. On his way out, however, the inmates lined up and spit on him. Mershaw went to Gen Pop and, feeling abandoned by his God, killed himself.
[Episode 07: "Plan B"]