Not sure how the Fed Govt can do anything about crime, other than deport and jail the threats to life.
Just get out of the way of the states, counties and cities and let them do their job.
They can start by deporting criminal illegal aliens and not let in any more. This is exactly what Trump plans to do.
Fed Govt can do everything about crime, by getting out of the way of local police, deport and jail the illegals re threats to life, and eliminate sanctuary cities.