History
Colonel Schoonover was the commanding officer of Frank Castle's unit when he was serving during the Vietnam War. He was heading a drug smuggling operation to finance anti-communist aid to the hill tribes.
After the war, Schoonover was running for US Senate, and afraid that any of his old team may talk about their past as drug smugglers, he hired the Sniper to assassinate them.
The Punisher subsequently forced Schoonover to confess his crimes. He then committed suicide.[1]