>>4128351 (pb)

Not at all. Evidence can move to and fro within any PD, FBI, etc. as long as a record of the custodial chain of possession is kept with the evidence. If that chain is broken and someone takes the evidence without recording the date and time it was taken and then places the evidence back in an "evidence locker", the evidence then becomes "tainted" legally and rendered useless. This is why the "magic bullet" in the JFK assassination would never have been allowed as evidence in a trial of LHO. It was allegedly found by hospital staff, then passed from pocket to pocket and finally noted as evidence by the Dallas PD. It would have been useless at trial though and LHO likely acquitted as that bullet tied him to the rifle which was allegedly found on the 6th floor of the Book Depository.