The team of outside attorneys helping President Trump navigate the Russia investigation has added another -- John Dowd.

Dowd tells CBS News the team's head attorney, Marc Kasowitz asked him to come on board at the end of May and has been working with Kasowitz, Mark Bowe, and Jay Sekulow since then.

Dowd is a veteran lawyer who has delved into D.C. politics before. In the early 1990s, he represented Sen. John McCain, R-Arizona, during the Senate ethics Investigation known as "the Keating 5."

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McCain and four other senators were accused of improperly intervening to help Charles H. Keating, Jr., the chairman of a financial institution that became the target of a regulatory investigation, resist regulators.

The investigation ended in early 1991 with a rebuke that McCain "exercised poor judgment in intervening with the regulators." But the Senate Ethics Committee also determined McCain's actions "were not improper nor attended with gross negligence."

In the 1980s, Dowd was appointed special counsel for the commissioner of baseball. The report he authored, on Pete Rose's betting on baseball games, led to Rose's lifetime banishment from Major League Baseball.