A D.C. service station owner was convicted in federal court here today of interstate transportation of stolen money in a massive check-kiting scheme involving--by the defendant's own estimate--some $70 million over a six-year period.

Eddy Marvin Thompson, 39, owner of Thompson's Texaco at 4000 Georgia Ave. NW, stood motionlessly before U.S. District Court Chief Judge Frank A. Kaufman as a jury of 10 men and two women returned guilty verdicts on all 20 counts.

Kaufman scheduled sentencing for June 9. The heavyset gas station owner faces up to 10 years in prison and a $10,000 fine on each count. His attorney, Clement T. Cooper, said he probably will appeal the conviction. Thompson remained free on personal bond today.

Thompson, who lives in suburban Baltimore, was accused of cashing millions of dollars in checks at an American Security bank in the District to cover overdrafts at a Citizens Bank & Trust Co. branch in Silver Spring.

Thompson acknowledged writing about $70 million in checks but contended he had no criminal intent and believed he had been extended a "line of credit" by an American Security branch manager and his assistant, who approved the checks for cashing.

What started out as a series of relatively small overdrafts seven years ago, amounting to a few hundred dollars a day, ballooned to more than $200,000 a day by early 1982, according to Assistant U. S. Attorney Steven A. Allen. The prosecutor said Thompson siphoned off cash for his gas station and tried to cover the overdrafts by cashing ever larger checks.

Allen told the jury the scheme worked this way:

On "day one," Thompson would have a balance of, say, $2,000 in his checking account at Citizens Bank. He would write a CB&T check for $10,000 and deposit it in his business account at American Security.

On "day two," Thompson would write another CB&T check for $10,000, but this time instead of depositing it, he would cash it at American Security. He would then drive back to Maryland and deposit the cash at CB&T. That would cover the previous day's $10,000 check before it was processed through the Federal Reserve Board clearinghouse in Baltimore during the night and returned to CB&T the next day.

On "day three," Thompson, needing more funds for his gas station, would write two CB&T checks, one for $10,000 and one for, say, $5,000. He would deposit the $5,000 check in his Texaco account at American Security, cash the $10,000 and then drive back into Maryland and deposit it at CB&T, again to cover the previous day's check.

On "day four," Thompson would have to write a check for $15,000 to cover both the original $10,000 overdraft and the additional $5,000 overdraft. He would cash the $15,000 check at American Security, then once again drive back to Maryland and deposit it at CB&T before the previous checks cleared.

In that manner, Allen said, the cycle continued on an almost daily basis for six years with the "float" increasing each time Thompson deposited additional money at American Security.

Thompson "had started a circle and had to keep it going or the whole thing would fall down," Allen said.

It came to a halt in 1982 when a federal currency task force of prosecutors, FBI, Internal Revenue Service and other agents came across Thompson's unusually large CB&T deposits during a routine audit. Further investigation showed that a former American Security branch manager, Luther Pinkard, and a former assistant, Dorothy Bierer, had approved Thompson's checks--which had grown to about $200,000 a day by early 1982--without filing so-called Currency Transaction Reports (CTRs) required by the Federal Reserve on all cash transactions over $10,000.

Pinkard and Bierer acknowledged their roles in the check-kiting process but denied receiving anything in return. They said they continued to approve Thompson's checks to protect their jobs and prevent discovery once they had become involved. Both have been charged with failing to file CTRs.

Though Thompson wrote checks totaling millions of dollars, American Security recovered all but $204,800--the amount of the last check Thompson wrote before his arrest.