Jeff Strode was a career blackmailer who tried to extort money from the wrong man and ended up dead on the bathroom floor.
Involvement with the Lone Gunmen
The Lone Gunmen were trying to find out who murdered Jeff Strode when they found Jeff Strode himself, alive and well though in FBI custody.
He explained that he had blackmailed a man who seemed to be cheating on his wife only to learn he was an FBI agent undercover with his partner as an importer. The woman online was his real wife. So when he showed up at the club to demand the money in person, Assistant Director Walter Skinner had to attack him in the bathroom and make it look like a homicide while the FBI hid Jeff Strode in a safe house.
He teamed up with the Lone Gunmen when trapped in the safe house with them. Given that Carol Strode had once been Carl Strode, they had realized that Jeff's sister Carol was in danger since there would be no one with that name born on that date which would make the Russians suspicious. They escaped and rushed to help Carol at the Club Tamarind sting but by the time they got there it was all already over.
The FBI had freed Carol Strode and apprehended the Russians. Jeff and Carol embraced, each happy that the other was alive.
A hacker with an impressive setup for dealing with his blackmail victims; using a pair of glasses with cameras in them he recorded his confrontations with those he blackmailed just in case one of them killed him. Though this must also mean that he inadvertently recorded vast amounts of evidence against himself...