How do you find out who called from a blocked number?

Can * 67 be traced by police?

"As soon as the call is placed, it can be tracked and traced to where it is being originated." ... Dialing *67 may cloak your call from other Caller ID-equipped phones, but not from your carrier or the authorities.2016-01-12

Can someone trace a blocked number?

Private numbers, blocked, and restricted calls can usually be traced. However, unknown, unavailable or out of area calls are not traceable because they don't contain the data needed for a successful trace.