A three-month investigation into alleged race-fixing at Ocean Downs Raceway near Ocean City, Md., ended last night when a leading harness driver was suspended and several drivers were subpoenaed to appear before a Worcester County grand jury, according to state police and a state racing official.

The allegations center on a July 28 race that investigators questioned because of what appeared to be an unusual payoff to bettors. But William Linton, executive director of the Maryland State Racing Commission, said last night that the suspicious practices had apparently been more widespread.

"Even before July 28 we were looking into it," he said.

Investigators said that a number of people at the half-mile track that night made unusually heavy bets on Via Mia to win and Fly Baretta, to come in second.

Robert Clark, 25, who was driving Fly Baretta, was suspended on Aug. 1 for five days after judges said he had deliberately helped "another driver improve his position." Clark, one of the leading drivers at the 38-year-old track, was suspended again last night, Linton said.

Via Mia, a 20-to-1 shot coupled with Fly Baretta, a 5-to-1 shot, paid only $46 in the $2 exacta. Ordinarily horses with those odds would pay $250, which means that an unusual amount of money was bet on that combination in this race. The combination $2 exacta of Via Mia with Worthy Jean, who finished in a dead heat with Fly Baretta for place, paid $217 even though Worthy Jean had only 2-to-1 odds.

It was unclear how many persons had been subpoenaed last night, but Linton said it was several. He added, however, that not all the subpoenas have been served. None of the names were available.

Racing officials last night stressed that the investigation had been initiated by the racing commission and state police were called at the racing officials' request. E. William Furey, chairman of the state racing commission, said the scope of any irregularities appeared "very limited."

According to a source involved in the probe, the racing commission conducted an undercover investigation in which one official gained the confidence of the drivers at the track. That official then prepared a report for the commission that said he had discussed fixing races with at least two drivers on several occasions.

"We had a race where we set a man down suspended him and we had a lot of talk about that," Stanton Richardson, the presiding judge at the track, said this week. "We had patrons very perturbed about it who said that the payoff came back short."

Ocean Downs President John Howard Burbage said in an interview last Monday that he was aware of the ongoing investigation.

"I do know that they're investigating one race here at Ocean Downs," said Burbage, a businessman who is also the mayor of the neighboring town of Berlin. "It was a payoff that didn't look right. I haven't seen anymore that looked like that again this year."

"I think it's a good idea to investigate ," Burbage said. "If patrons know the commission and myself are investigating, they know everything's on the up and up."

Burbage said, however, that he was unaware of any other details of the racing commission's inquiries.

Burbage said that Ocean Downs has seen greater increases in attendance and nightly betting in the past three years than any other raceway in the state. Average nightly wagers have increased from the $126,000 recorded during last year's betting season to $141,000 this year, he said.

The track operates from May until September and attracts as much as 60 percent of its patronage from the tourists staying in nearby Ocean City who venture across the Isle of Wight Bay for an evening of gaming.

"This is a small family track," Burbage said. "If there is any cheating going on, it is probably at the larger tracks where a lot of money is [being bet]."