since we have no clue what we are working on....
all mopar have a nuetral safety switch on the side of the transmission....your linkage is problem not adjust correctly or someone bypassed the switch....
the starter relay switch has a G terminal that sends a wire to the NSS....went the trans is in neutral or park...the NSS grounds itself allowing the engine to turn over....
if it is starting in all gear...then the Starter relay is receiving a ground all the time...either thru the NSS or bypassed to ground