He will fill a vacancy created by the unexplained resignation of Thomas Comer, who two weeks ago resigned as CEO without giving a reason for his departure.

Aon said in February it was looking into divesting itself of the company. That announcement came as investigations of retail brokers raised concerns that they could be steering wholesale placements to the wholesale firms they owned.

Patrick G. Ryan, chairman and CEO of Aon, said in a statement: "Dave is one of the most respected and experienced executives in the wholesale insurance business. His knowledge of Swett & Crawford, as well as his industry stature and expertise, will serve us well in the time ahead. I am confident in his ability to lead the company through its divestiture from Aon in a manner that will benefit all concerned."

Terry Winkler will continue to serve as chairman of Swett & Crawford. He and Mr. Hartoch, along with executive committee members Neal Abernathy, Bob Greenebaum, Ed Magliaro, Don Shorey and Terri Snell, "will steer the firm as its future course is determined," Aon said.

The current Swett & Crawford Group is comprised of Swett & Crawford, Sherwood Insurance Services and Insurance Brokers Service, which Aon combined in 2002. Swett & Crawford joined Aon in 1997.