Brock was a member of the Arkansas Project, created to destroy Bill Clinton. He has since repented and is now working for Hillary; she is an incredibly forgiving individual.
http://www.boomantribune.com/story/2016/5/24/111749/271
According to R. Emmett Tyrrell Jr., editor-in-chief of the [American] Spectator, the idea for the Arkansas Project was hatched on a fishing trip on the Chesapeake Bay in the fall of 1993. The Arkansas Project name that later became famous was conceived as a joke; the actual name used within the Spectator and the Scaife foundation was the Editorial Improvement Project.
Project reporter/investigators were hired, including David Brock, who later (after reversing his political stance) described himself as a Republican hitman, and Rex Armistead, a former police officer who was reportedly paid $350,000 for his efforts. Also assisting the project was Parker Dozhier, a bait shop owner who was reportedly obsessed with bringing down Bill Clinton. They were tasked with investigating the Clintons and uncovering stories tying the Clintons to murders and drug smuggling as well as adultery.
According to Brock, Armistead and Brock met at an airport hotel in Miami, Florida, in late 1993. There, Armistead laid out an elaborate Vince Foster murder scenario, a scenario that Brock later claimed was implausible. Regardless, by the end of 1993, Brock was writing stories for the Spectator that made him a lead figure in the drive to expose Clinton.
David Brock isnt the most reliable reporter of fact, but the basics are not now in dispute. We may never know if future Solicitor General Ted Olsen told Brock that the American Spectator should publish speculation about Vince Fosters death, even though he himself believed that speculation was false, because doing so would turn up the heat on the administration until another scandal came along. But we know that the Spectator and many other shadowy right-wing outlets did exactly that.
Whatever you think of him, the fact remains that the Vince Foster murder conspiracy story was concocted by conscienceless and cruel opponents of the Clintons, almost none of whom have apologized precisely because they have no conscience.