Highmark chairman of the board J. Robert Baum, a Spring Grove resident, has taken over as CEO of the insurer.

The move came after company's board announced the unpaid leave of CEO Kenneth Melani, 58, who faces charges of simple assault and defiant trespass relating to a fight with the husband of an employee he was having an affair with.

The charges led to a series of emergency meetings among the leadership of the company, which has 5,000 or more employees in the Camp Hill area in addition to those based in its Pittsburgh headquarters. Highmark provides insurance to more than 4.8 million members in Pennsylvania and West Virginia.

"This really came to a head on Wednesday," Baum said in talking about the situation on Friday. "And I think the first reaction was sadness, because we loved this guy. He's a great strategic thinker and had been driving our growth and success."

Melani allegedly showed up Sunday afternoon at the home of Mark Myler, who is married to Melissa Myler, The Associated Press reported.

She told officers she has been having an affair with Melani since shortly after he hired her to work at Highmark in October 2011. In January, according to a criminal complaint, Melani's wife discovered the affair and told Mark Myler.

That prompted Melissa Myler to move out of their Allegheny County home and in with Melani, according to the complaint.

Melani was placed on an unpaid leave and on Thursday Baum was named the acting CEO on an interim basis.

"I think anybody who's been a board chairman understands if there's trouble in the hot seat, then you have to move in," Baum said.

Though it wasn't his plan, he said he was ready to assume the role for the time being.

"We've gotten our team together and are just holding hands at this point to make sure nothing is lost," he added. "But I think we know how to keep this company growing as it was."

Baum, who lived in Hanover for more than 20 years before moving to Spring Grove in 1988, has been Highmark's board chairman since 2005 and began his tenure in 1980 on the Pennsylvania Blue Shield board in Camp Hill.

He's also a professor of entrepreneurship at the University of Maryland, and has started and operated several businesses in the Hanover area.

Along with the board of Highmark, Baum is on the board of the Susan P. Byrnes Health Education Center in York, the Whitaker Center for Science and the Arts in Harrisburg and the Governor's Early Learning Investment Commission.

Baum is assuming his new role at a critical time for the company, which is an independent licensee of Blue Cross and Blue Shield Association.

The company is working to secure a multi-year contract with the University of Pittsburgh Medical Center, to complete a pending acquisition of the West Penn Allegheny Health System and to address the challenges of making health care more affordable, Baum said.

The emphasis on affordability is a priority, he added.

"We want to keep the cost of health care down," he said. "And we spend a lot of time on keeping the availability to our members, so they can go pretty much anywhere and use their insurance card."

hfaulhefer@eveningsun.com; 717-637-3736, ext. 140