The initial assassination attempt was carried out by sabotaging an environmental subsystem, which exploded- injuring but not killing the Hades crewman.
When a second attempt was made on the crewman's life in sickbay, it became apparent that someone was trying to assassinate the Dopterian member of the crew.
An investigation was opened and when the remains of an Orion Disruptor Grenade were found, all indications pointed to the Orion Syndicate.
Baylon Trinin managed to infiltrate the organization on the station to a lesser degree, but it was enough to allow the other members of the Hades crew to locate and deal with Crel.
The Dopterian was killed in a firefight with Starfleet personnel on the station.