Then the suspect is released. After an arrest is made.
It is not up to the police to prove anything.
They have a complaint. They have names. They make arrests. They engage detectives who ask questions. The answers are used to either build a case to profer charges and turn the case over to the Attorney General's office...or release the suspect. It's a process. This flatfoot a-hole, chief Williams has decided to abrogate his responsibility.
The police have to have probable cause to charge somebody, otherwise it’s a multi-million dollar settlement. You can’t go pick somebody up because you thought they did it.
If you don’t believe me, go and try to make a citizens arrest without probable cause and see what happens to you.
The police have to have more than a name and a complaint. They need grounds for an arrest, otherwise you could find yourself in perpetual lockup because you have a neighbour who can lodge complaints against you all day long.