Riley McGrath (a.k.a. Martin Holds) was a presumed Vesper. He died in 2000.
Riley invited Sinead Starling and Ted Starling, when they were in the Olympic Mountians in Washington State, to go rock climbing. However, Ted didn't want to go rock climbing, so Sinead took him back to the lodge where they were staying and went on her own. Riley died in 2000.
In Shatterproof, Damien Vesper III posed as Riley McGrath. He met the hostages in The Black Forest, Germany, and he said that he was Martin Holds. Then the Vespers arrive and they fake kill Riley/Martin, because Damien Vesper III was posing as Riley/Martin, and Damien III was Vesper One.
The code on Card 283: Robot Spider said "Riley McGrath". This may be referring to the same person.