A second District of Columbia police officer has been arrested in connection with the slaying of a fellow officer's wife whose body was found Saturday in Charles County, Md.

Harry Jennings, 28, an eight-year veteran of the force, was charged Saturday night with being an accessory after the fact in the slaying of Irene Skalkowski, 26, of Takoma Park, Md., the Charles County sheriff's department reported yesterday. Jennings allegedly helped to bury the body, according to a police source.

Jennings was arrested about eight hours after Steven John Shalkowski, 31, the victim's husband and an eight-year veteran of the District's police force, was charged with first-degree murder in his wife's death.

Fellow officers said Shalkowski and Jennings were close friends.Both came on the force within a week of each other and had worked together for a while in the 7th District police station in far Southeast.

Shalkowski left the 7th District more than two years ago, but he and Jennings remained good friends, the other officers said.

Shalkowski, who was described as an expert marksman, and Jennings often went hunting together, one colleague said.

The discovery of the body and the arrest of the two officers ended a search for the woman that began after Shalkowski reported her missing on Oct. 28.

That was six days after Irene Shalkowski was killed, according to Jim Gartland of the Charles County Sheriff's Department. Gartland said yesterday that Mrs. Shalkowski was killed at about midnight on Oct. 22 in the couple's car.

The car was parked on Rte. 301 near Rte. 5 close to a shopping center when she was shot and stabbed to death, Gartland said. Early the next day, he said, she was buried in an 18-inch deep grave about three miles away in a wooded area outside Waldorf, Md.

After Shalkowski told Prince George's police that his wife had been missing for five days, the police entered her name in the computer that links missing persons reports with police departments throughout the country. They also listed the car that she had been in, a 1973 Dodge Dart.

Randy Bowers, a deputy with the Frederick County, Va., sheriff's department, said yesterday that he spotted the car Oct. 28 on a country road near Gainesboro, Va., about 100 miles west of Washington.

"There was nothing to make me think that it [the car] was something unusual," he said.

He said he learned that the car was registered to Steven Shalkowski in Takoma Park, Md. He said he assumed that the driver had car trouble and had left the car. "I thought about writing him a letter to tell him to come and get his car," Bowers said.

Bowers said he was told by a resident who lived nearby that the car had been there for some time. The resident also reported he saw a man park the car, get out and get into a second car.

A few days later, Bowers discussed the car by telephone with Prince George's County police. Investigators from the Hyattsville police station, where Shalkowski had reported his wife missing, went to the area to check the car early in November.

Two or three weeks later, Bowers said he found a reddish-tan billfold belonging to Mrs. Shalkowski in the woods about 50 feet from where the car was discovered.

He said he reported the discovery to Prince George's County police. The Hyattsville detectives began to suspect foul play and turned the investigation over to the homicide unit on Nov. 21, according to a Prince George's County police spokesman.

Bowers said a Prince George's County homicide detective came to the area last Tuesday and talked with the resident who reported seeing the car abandoned.

Officers interviewed relatives and friends of the couple last week and Shalkowski was questioned extensively early Saturday.

Shortly thereafter, Irene Shalkowski's body was found. She had been shot once with a shotgun and stabbed four times in the chest, according to Gartland.

Prince George's County divers yesterday searched the Potomac River beneath the Wilson Bridge for the shotgun used in the shooting because of information that the weapon would be found there.

One diver stood on the bridge at the Maryland end and tossed over a shotgun similar to the one used in the slaying to test how far the weapon would go from the bridge before striking the water. Then the diver climbed down a rope into the chest-deep water to look for the shotgun.

Other divers working from boats also searched the river, but as of last night the weapon used in the slaying had not been found.

After Mrs. Shalkowski's body was discovered Saturday, the Charles County sheriff's department arrested her husband and charged him with first-degree murder. He was being held without bond last night in the county's detention center in La Plata, Md.

Jennings was arrested at his Waldorf, Md., home about 7:30 p.m., by Charles County sheriff's deputies. He was being held on $20,000 bond in the county's detention center.

Gartland said that Shalkowski, who joined the District police force in May 1971, resigned from the force on Saturday night.

Jennings, who also joined in May 1971, has been suspended without pay, Gartland said. tBoth are to appear in Charles County Circuit Court for a bond hearing today.