“No one, including the appeal panel, has ever disputed Dr. Charest's personal contribution to the groundbreaking tetracycline inventions,” O’Reilly said. “The only issue the panel decided was the relative value of the pioneering tetracycline patents and the latter added method patent; a decision that was at odds with Harvard’s [intellectual property] policy.”

In an emailed statement Wednesday, Charest called interactions with Harvard about the dispute “exceedingly difficult and frustrating.”

“There has been a lack of collaborative spirit and transparency in the process from the outset,” Charest said. “I have openly explored every avenue to work toward resolution of the various ‘valuation issues’ over the years.”

According to O’Reilly, he and Charest wrote to Harvard and Myers on May 28 requesting a settlement, to which Harvard and Myers’s counsel responded through a letter refusing the offer on June 27.

Myers did not respond to a request for comment, and Derek Barton, a senior administrative manager for research who manages Myers’s laboratories, could not be reached for comment this week.

—Staff writer Madeline R. Conway can be reached at mconway@college.harvard.edu. Follow her on Twitter @MadelineRConway.

This article has been revised to reflect the following correction:

CORRECTION: July 9, 2013

An earlier version of this article misquoted a statement from former Ph.D. Mark G. Charest about his interactions with Harvard regarding a royalties dispute. In fact, Charest claimed that from the “outset,” not from the “outside,” the process has lacked collaboration and transparency.