There have also been allegations that some in the LAPD are members of street gangs. It's probably common, especially in large cities. The Vice Lords are a major street/prison gang, very big in Chicago. That they are embedded in the police explains a lot when it comes to out of control crime, especially something like the protection of open air drug markets. They would also be useful in pushing the narrative that all police are 'thugs with badges', as is happening in Memphis.