A former police informant testified today that he helped Prince George's County police set up a phony robbery of a 7-Eleven store in 1967, luring two unsuspecting participants to the scene and then "throwing 'em to the wolves" when waiting police shot and killed one and arrested the other.

Speaking via video tape recording made in Indiana and displayed on a color television screen to a civil jury here, informant Sydney Hartman testified that Det. Joseph D. Vasco Jr., now the second highest ranking official in the county police department, asked him to recruit two armed thieves and accompany them to a 7-Eleven store in Chillum on Nov. 26, 1967. In exchange, he said, Vasco promised to get a check-forging charge against him dropped.

Police who were staked out at the store then shot and killed one "recruit," William Clyde Harris, 25, and arrested the other, David E. Wedler, 19, according to Hartman, after the three brandished handguns in the store, snatched money from an officer posing as a clerk, and attempted to flee.

"I did it to save my a--," said Hartman. Referring to Harris and Wedler, he said, "I was stacking 'em up. . . throwing 'em to the wolves."

Hartman's testimony came in the tenth week of a complex $9 million civil rights trial in which Wedler, Harris's family, and others have sued three members of a so-called police "death squad" for allegedly staging a series of five holdups and burglaries in 1967.

Hartman, who lives in Indiana and refused to come to Maryland for the trial, was questioned by attorneys near his home, with his testimony videotaped for the jury here.

The plaintiffs contend that the five stakeouts--in which two suspects were shot and killed, one wounded, and several others arrested--violated 14th amendment rights to due process.

Police have denied the allegations, contending Hartman and other informants reported planned robberies and burglaries to them, and detectives then routinely staked out the targeted stores.

Hartman, testifying about the last of the five incidents, provided details about his alleged relationship with Vasco and his alleged efforts to orchestrate a "robbery" of the Chillum 7-Eleven with two companions.

Under questioning by plaintiffs' attorney Barnet D. Skolnik, Hartman said there had been a rash of convenience store holdups in the Chillum-Langley Park area and police wanted them stopped.

Hartman said Vasco asked him to recruit two armed men with prior criminal records from among his street friends and persuade them to commit a 7-Eleven robbery.

With some difficulty, Hartman said, he "lined up" Wedler and Harris. He said he picked the Chillum 7-Eleven, telling his companions that the manager there was his cousin who would allow them to "rob" him. The cousin would then report the loss to his insurance company in a greater amount than actually stolen, thus making the effort worth it for all of them, Hartman said.

Next, Hartman said, he tipped Vasco that the robbery was about to occur. He said he told Vasco he would be wearing a red shirt so that waiting police would not confuse him with the other two participants.

Then, armed with pistols and wearing stocking masks, the three barged into the store and grabbed a bag of money, Hartman said.

As they fled, he said, police hiding in nearby woods, shot and killed Harris and arrested Wedler and himself.

Hartman was later released without charge.

Wedler was convicted of assault and imprisoned for two years.

Police have said Harris was shot only after they ordered him to halt and he fired at them.