When Dr. Glen E. Slayman of Beaver, Pa., first visited Riverdale Baptist Church in rural Prince George's County last year, he seemed to be "a ray of hope out of the dark clouds" to the church's pastor, the Rev. Herbert Fitzpatrick.

To a congregation that was $500,000 in debt and on the verge of selling off its property, Slayman, a Bible-toting evangelist who claimed to be both a construction contractor and a criminologist, held out the promise of a $2.5 million grant from the "Mellon Foundation" that not only would pay off the debt but would allow the church to build a new wing for its school.

All the congregation had to do, Slayman said, was pay an architect who shares his office $10,000 to begin drawing up plans. He would take care of the rest.

Four months after they handed over the money, the congregation of Riverdale Baptist Church has not gotten its grant. The foundation "contact" Slayman claimed to have has turned out to be a clerical worker in a Mellon bank branch 25 miles from Pittsburgh. Officials of the Mellon Bank Foundation in Pittsburgh say they have never heard of Slayman and don't normally make contributions to churches.

In the last few days Fitzpatrick and his business manager have concluded, that -- as Fitzpatrick put it -- "we've been taken." And, apparently, they are not alone.

Two other churches, Seabrook Baptist Church, also in Prince George's County, and Shenandoah Bible Church in Martinsburg, W.Va., have also reportedly made payments to Slayman's architect in hopes of receiving grants. They're still waiting, too.

"it sounded so good, what he told us," Fitzpatrick said. "And we were afraid because of our financial problems -- we didn't want to look a gift horse in the mouth."

Slayman did not return a reporter's phone calls over a period of two days. A man in his office, who refused to be identified, said the grant for the Seabrook church was on the way and that the Riverdale Church would not get a grant because they still owed the architect $18,000. He claimed that Slayman, in his role as a criminologist, was in fact investigating the Riverdale Church and its pastor for misuse of funds.

The Rev. Mr. Fitzpatrick and his business manager, who offered documents to support their case, said they had been fooled by a man who had dazzled them with his evangelical manner, his seeming care for their church, and his glowing descriptions of millions of dollars flowing from foundations to churches through his work.

The Riverdale ministers told a story of how, desperate for funds, they had been persuaded by Slayman that the answer was to embark on a new construction project using Slayman's architect friend, Clarence V. Blezard, the Mellon Bank Foundation for grants, and Slayman as the eventual contractor.

"He makes a beautiful argument," said Fitzpatrick. "We had him down here to speak to [church members] and he came through with flying colors. He made every skeptic a believer."

Foundation officials and fund-raising organizations contacted by The Washington Post said the Slayman's tactics for winning grants, as alleged by officials of four different churches, were highly irregular and that much of what Church officials say Slayman told them about winning grants is not true.

Maryland officials said Blezard is not listed in their records as being registered in Maryland -- which is required of all architects who do work in the state -- although Blezard is registered in Pennsylvania. Belzard did not return a reporter's phone calls.

Fitzpatrick and the Rev. Fred Snowden, the church's business manager who handled Riverdale's long negotiations with Slayman, said that the church sought out Slayman in the spring of 1979 after hearing that Seabrook Baptist Church in the northern part of the county expected to recieve a grant of over $6 million from "the Mellon foundation" through Slayman.

Officials of Riverdale Baptist needed money badly, the two men said, because they had recently completed a new church building that had cost $500,000 more than expected. They did not have money to pay the contractors, and were thinking that they would have to sell some of their extensive holdings along Route 202 to raise it.

Soon after they first talked to Slayman Fitzpatrick and Snowden said they went to visit him in his office in a restored clapboard house in Beaver, a small town about 35 miles northwest of Pittsburgh.

Slayman, they said, told them about his construction business, and claimed to have obtained $14 million in foundation grants for Methodist churches before deciding to "branch out" to Baptist churches.

Slayman, according to the Riverdale pastors, said he had won a degree in criminology from Florida State Christian University, and had worked as a consultant to the FBI and as a bodyguard for former Alabama Gov. George Wallace.

Florida officials said that Florida State Christian University has been out of business since 1972, when it was served with an injuction prohibiting it from operation because of its failure to meet state standards.

Aides to Wallace said Slayman had never worked with the governor, and the FBI said it has no record of any work by Slayman.

Slayman, a burly, middle-aged man, once drove Snowden in a new Cadillac to his mansion, complete with an indoor swimming pool, on a hill overlooking Beaver. He convinced the Riverdale congregation leaders that he could easily win them a $2.5 million grant from the Mellon Bank Foundation.

To convince them, Snowden and Fitzpatrick said, he called Pauline Dragovitch, an employe of the nearby Aliquippa, Pa., branch of the Mellon bank. Dragovitch, he said, reviewed all grants for the Mellon Foundation.

Snowden said he talked with Dragovitch on the phone, and that she told him that "the Mellon foundation did not give grants for existing debts, but that if we built the new school complex, we could definitely get a grant."

"She said that I didn't need to call her or anyone else," Snowden said. "She said I should just leave everything to Slayman, and that I would have a very good chance if I let Slayman do it."

Another pastor who has been talking to Slayman about receiving a grant, the Rev. Dino Pedrone of the Open Door Church in Chambersburg, Pa., also said that Slayman told him a grant might come from the Mellon foundation and that Dragovitch was the key to it.

"He said the Mellon Foundation was a good possibility and that he had given my name to Mrs. Dragovitch," Pedrone said. "I got the impression that she had influence -- that she was a director of the foundation or managed it."

In a telephone interview, however, Dragovitch, who is an administrative assistant to loan officers in the small bank branch at Aliquippa, said she had nothing to do with the Mellon Bank Foundation or any other foundation.

She said she knew Slayman as a contractor in the Beaver area and that "I talked to him when I see him." She denied however, that she knew anything about Slayman's plans to get grants for churches.

Dragovitch said she remembered talking to Snowden, but said she had told him only that "many foundations give grants and if their church was qualified they could get one." She added that a second church, whose name she did not remember, had contacted her once at home and asked her if Slayman could get them grants.

"I thought it was peculiar," she said of the calls asking for her advice, "I was really surprised."

Snowden and Fitzpatrick said that after talking to Dragovitch, they were willing to go ahead with Slayman's proposed project, and were told at first by Slayman that they would not have to put up any money to receive the grant.

Later, however, they said Slayman told them that to receive the grant, they must first have architectural plans prepared, and that the only person who could do the plans to the foundation's satisfaction was Blezard, the architect who worked a floor above him in Beaver.

Riverdale first paid Blezard a $2,000 retainer, and then last February was presented with another bill for $16,6900 which Slayman said they had to pay before the grant could be obtained.

Uncertain whether to pay the money, Snowden and another Riverdale official visited Slayman again. Slayman assured them they would get the grant if they paid, they said, and showed them a letter, signed "Pauline Dragovitch," which Snowden said spelled out that Riverdale would get a grant if it paid for the completion of the plans.

Snowden said Slayman refused to give him a copy of the letter.Dragovitch, when contracted by The Post, denied writing it.

Snowden and Fitzpatrick said they told Slayman the chruch did not have the money to pay the bill, so Slayman offered to pay $8,450 to Blezard if the church would pay $8,450. The church members agreed, and after personal donations from its group of deacons and trustees, paid Blezard $8,450, and received in return a copy of an uncanceled check from Slayman to Blezard for $8,450.

The Riverdale ministers said that the only tangible thing they have received in return for their money so far is a single sheet of architectural draft paper with two rough sketches of the proposed school wing on it. Blezard also gave them a rough room plan of the proposed building before they agreed to pay him, they said.

Fitzpatrick and Snowden said that Slayman first assured then that they would be approved for their grant by last Jan. 1, then said they would have the money by March 1. Two weeks ago, Fitzpatrick said, Slayman assured him in a telephone conversation that he was going to make a final presentation to the Mellon board on May 29, and Snowden said Slayman told him on June 3 that "everything was going fine and Mrs. Dragovitch was working on it."

Slayman is also reportedly seeking funds for the Seabrook Baptist Church, which has sold its property bought a new piece of ground and plans to build a new church with Slayman's help. The Rev. Dan Allen, pastor of the church, said he had given Slayman or Blezard "more than" $40,000, but later would not verify the amount.

Allen said he trusted Slayman, and refused to say how Slayman might be getting the church a grant. His wife Hazel told a reporter that the church expected to receive a multi-million dollar grant from the Mellon foundation through Slayman, but had not receivied any funds yet.

The Rev. Don Smith of the Shenandoah Bible Church in Martinsburg, W. Va., said he was also working with Slayman to win a grant and had paid Blezard an initial $2,000 retainer fee.

Smith said his church wantd to build a new school, and that Slayman had helped him draw up plans for a facility that would cost around $1.5 million. Smith said Slayman told him that once the plans by Blezard were complete they would work to win a grant from a foundation, but said Slayman did not mention any particular foundation.

"I personally think things are on the up-and-up with Slayman," Smith said. "Everything he's sent to me so far has been okay." Smith said he did not know whether Blezard intended to send him additional bills for plans, or how much the bills would be. CAPTION: Picture, The Rev. Herbet Fitzpatrick says his church paid $10,000 for these sketches and the promise of a grant. By John McDonnell -- The Washington Post