Duhh. Why not just arrest the criminals and force them to testify against their accomplices??
Easier said than done. This is an ongoing problem according to people I know in law enforcement. Say a shooting happens in these ghetto areas. Police arrive, and typically nobody saw anything. Nobody can testify. Nobody can identify a shooter or a getaway car or provide any evidence. There are people lying there dead or injured. There may have been crowds of people present when shots were fired. But generally the police can’t find anyone who saw anything. Officially anyway they didn’t see what happened .