District of Columbia police yesterday released a composite drawing of a man wanted in connection with the attempted murder Wednesday of Assistant U.S. Attorney Barry L. Lelbowitz.

Homicide detectives are seeking to question a dark-skinned black man with a large build whom they believe to be about 35 to 40 years ago.

Leibowitz was struck by a .22-caliber bullet just above the right hip as he walked to work in the U.S. District Courthouse here. The gunman, a passenger in a car driven by another man, fired through the open window of the car from about 6 feet away. The men then drove off at a high rate of speed.

Leibowitz was released from George Washington Univesity Hospital Thursday, And was back at work for a few hours yesterday. The bullet still is lodged in fatty tissue about 1/2 inch into his body, but doctors said they did not need to remove it immediately.

Leibowitz has been leading a year-long investigation into an intricate drug ring that has been smuggling millions of dollars of herion into Washington.

Authorities investigating the shooting believe the attack on Leibowitz was a warning to witnesses and potential witnesses to remain silent. Some police believe the murder attempt was the work of professionals who bungled the job. Leibowitz saw his assailant fire at him with a gun equipped with a silencer.

At least two witnesses or potential witnesses connected to the ring are believed to have been killed, and investigators are looking into the posibility that other drug-related deaths in the District of Columbia may be tied to the operation.

Law enforcement officials have described the ring as well structured and difficult to penetrate, with a drug pipeline from Southeast Asia through Amsterdam into the United States.