The mystery backer behind Samuel P. Coffman's bid to outmaneuver Harvard for purchase of the Bennett St. MTA Yards was identified yesterday as a nationally-prominent multimillionaire New York City real estate developer or financier who graduated from Harvard but now seems alienated from the University.

Sources at Harvard indicated that the anonymous backer may well be antagonistic to the University, which has rejected gifts from him in the past because of "strings attached."

Loyal Harvard alumni located high in the financial hierarchy of New York City, Boston, and Chicago were unable to provide more positive identification. However, sources at the New York Stock Exchange will be contacting business colleagues today in an effort to identify the backer.

Reached in New York, William Zeckendorf, Jr., of Zeckendorf Property Corporation, said his firm had been contacted "by a bidder interested in the land." However, Zeckendorf added, "we are not involved; we have a policy opposed to bidding against a University." Zeckendorf also stated that "the backer has an obligation to make his name public."

Robert Tishman, president of Tishman Realty and Construction Company in New York, and Ian Woodner '39, a New York financier, were both unable to name the backer.

Coffman, a Boston developer, has refused to reveal his anonymous supporter either publicly or to the MTA Board of Directors. Coffman's bid is at least $2 million higher than Harvard's $5,010,000 offer. He has claimed "my development plans will run as high as $100 million."