Patton first joined Oak Hill in 2001 to focus on transactions in the healthcare industry, most recently working out of the firm’s Silicon Valley office. His deals include Ascension Health Care Network, Butler Schein Animal Health Supply, Metrika and Vantage Oncology. Prior to Oak Hill, Patton spent time at Morgan Stanley Capital Partners and also in Morgan Stanley’s (MS) mergers and acquisition department.

The change comes as Oak Hill has begun talking to investors about raising a fourth fund. The Stamford, Conn.-based firm’s cornerstone investor is the Robert Bass family, but it also solicits third-party capital. Its third fund closed in mid-2009 on $3.8 billion in capital commitments, after an 18-month process. Through last June, the fund featured a 7.9% internal rate of return (IRR) and 1.3x investment multiple, according to CalPERS. It was more than 72% called down.

Oak Hill is not specifically replacing Patton, but last year did promote three principals to partner: Scott Baker, Scott Kauffman and Kevin Mailender. None of the firm’s 10 partners has a healthcare focus, although one of its four managing partners — Steven Gruber — has been known to work on healthcare deals (along with business and financial services).

A firm spokeswoman declined to comment on Patton’s departure. In an email, Patton said that he will continue to serve as an advisor to Oak Hill and its portfolio companies.

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