An 11-month FBI search for 5000 rare coins stolen from the Fogg Museum paid off this week, as FBI agents closed in on nine suspects and recovered half of the missing coins.

The surprise announcement that about 40 per cent of the coins had been recovered and five suspects in five different towns had been arrested came Tuesday. By Thursday a sixth suspect was nabbed in Jamaica Plain, and yesterday another 866 coins and three suspects were found in Canada. FBI agents are still searching for about 2000 coins and one suspect.

The rare Greek and Roman coins, valued at about $2 million, were heisted last December 2, in an ingenious caper that would make great material for a television script writer.

A man with a package walked into the Fogg one afternoon, and asked to leave a package for a Mr. Ryan with the guard.

At 12:30 a.m., a lone gunman knocked on the door of the Fogg and told the night watchman that he was Mr. Ryan and had come to pick up his package. When the watchman opened the door, the gunman and several accomplices forced their way in and used the watchman's keys to open the display cases for the coins.

The theft is believed to be the largest ever involving rare coins.

The arrests this week were the culmination of an investigation involving Massachusetts, Rhode Island, FBI and even international law enforcement agencies.

The coins that were recovered Tuesday were found in the woods near Lincoln, R.I. One of the suspects arrested then, Anthony Vaglica, worked in Widener Library on a prison work-release program in 1972.

The three suspects arrested yesterday in Canada in possession of the coins have not been linked directly to the robbery, but were charged with possession and transportation of stolen property.

Since the coin heist last year, security precautions at the Fogg have been tightened and the old director, Daniel J. Robbins--whom many blamed for loose security that permitted the coin theft to occur--has retired.