Investigators for the congressional Iran-contra committees are examining whether proceeds from a $100,000 contribution to the Heritage Foundation, a conservative think tank, ended up in overseas bank accounts set up at the direction of Lt. Col. Oliver L. North to arm the Nicaraguan contras.

Phillip Truluck, executive vice president of the Heritage Foundation, said last night that congressional investigators have interviewed foundation officials about the donation, made in 1985 by a wealthy Pittsburgh businessman interested in financing a project on Central America.

Truluck said the $100,000 was subsequently used to finance a grant the Heritage Foundation made to an organization headed by Richard R. Miller, a public relations official linked to North's private fund-raising network for the contras. Miller and conservative fundraiser Carl R. (Spitz) Channell have pleaded guilty to a charge of conspiring to defraud the government by raising tax-deductible donations that went for military assistance to the contras. North was named in court as a co-conspirator of Miller and Channell.

Truluck said the October 1985 grant to a Miller organization, the Institute for North-South Issues, was for the distribution of information on U.S. Central American policy and for another project on Central America. But he said the Heritage Foundation has been unable to determine how the money was spent.

During North's testimony to the congressional Iran-contra panels yesterday, Rep. Dante B. Fascell (D-Fla.) briefly asked North if he was aware of the donation, which was made by John F. Donahue, identified as the president of Federated Investors Inc. in Pittsburgh. North said Donahue's name "does not ring a bell."

North said he was also unaware of any tie between Donahue's contribution and the Heritage grant to the Miller organization.

The fired National Security Council aide acknowledged that at his direction Miller set up a Cayman Islands account called I.C. Inc., later renamed Intel Co-Operation Inc., used to funnel more than $1 million to the main Iran-contra account in Switzerland, Lake Resources Inc.

Documents released by the committees yesterday appeared to indicate that investigators have concluded that $80,000 of the $100,000 Miller's group received from the Heritage Foundation ended up in Miller's Caymans account, and that at least $7,300 was sent on to the Lake Resources account.

Truluck said Donahue was referred to the Heritage Foundation by Clyde (Terry) Slease III, then a lawyer for Richard Mellon Scaife, a wealthy Heritage contributor from Pittsburgh. At about the same time, Truluck said, Miller was introduced to Heritage officials by Roy Goodson, an intelligence expert who also was a consultant to the NSC.

North testified yesterday that Goodson and Slease took part in a White House meeting on "nonmilitary . . . Central American activities" along with former national security adviser Robert C. McFarlane. North said he did not recall details of the meeting. North also said Goodson had provided assistance to him, but declined to publicly discuss Goodson's work.

Goodson declined to comment last night.