John McClellan was an detective with the Los Angeles Police Department's Public Disorder Unit where he worked on a number of cases under the supervision of Irvin Irving. He investigated the theft of a gun from the home of Sam Weiss in June of 1988. He worked with Irving to derail the investigation into the murder of Rebecca Verloren, and he participated in the enforcement actions leading to the dismantling of the Chatsworth Eight gang.
When Irving was promoted up in the ranks, he brought McClellan along with him. When Irving was sidelined to the Office of Strategic Planning, McClellan again went with him.
In May of 2005, McClellan came to the home of detective Harry Bosch to talk with him concerning the unsolved 1988 murder of Verloren. He told Bosch that he cleared all of the members of the gang, in particular Roland Mackey and Billy Burkhart, because they were under surveillance at the time and therefore could not have committed the murder. He reminded Bosch that there had been no sign of forced entry into the house, meaning that the killer had gone inside earlier and hid until that night.