On Tuesday, Lee asked Attorney General Eric Holder to make sure all civil rights statutes were properly enforced.
Last Thursday, a jury convicted Mehserle of involuntary manslaughter in Oscar Grant's killing.
The Justice Department replied by saying it and the FBI have an open investigation into the fatal shooting, and will conduct an independent review after Mehserle's sentencing.
Oakland Mayor Ron Dellums said he also would ask the Justice Department to get involved at the request of Grant's family.
