An off-duty D.C. police officer who acts as spokesman for the police force early yesterday shot and critically wounded a man who had allegedly followed him with a machete on his way home to Prinse George's County.

The man was in critical condition yesterday at Prince George's General Hospital.

Police said the incident occurred shortly after the police officer, Joseph C. Gentile, turned off Rte. 50 onto Rte. 197 about 2 a.m. and saw a car coming up on his left, moving erratically. When the car, a silver Honda, pulled up alongside him at a stoplight, Gentile rolled down his window and asked if the driver needed help. The man "was incoherent and mumbling," and Gentile drove off, watching the man in his rearview mirror, according to Prince George's police spokesman Sgt. Robert Law.

As Gentile continued on Rte. 197, the man turned a corner, but quickly made a U-turn and began to follow Gentile's car as he continued down various streets toward his home, police said.

On Woodhaven Lane, Gentile, believing the man was following him, pulled to the curb, according to Law. The Honda stopped behind him and Gentile got out of his car, when he saw the man stepping from the Honda. As the man approached, Gentile saw that he was carrying a machete, police said.

The man began swinging the machete, striking Gentile's car, Law said. When the man "charged him" with the machete, Gentile pulled his service revolver and fired twice, striking the man in the chest, and left arm, Law said.

Law siad that Gentile did not know the man, who is 38 and lives in Lanham.

Gentile's superior in the D.C. Police Department's Public Information Office is conducting a routine administrative investigation of the incident, as would be done in the case of any shooting involving a policeman, according to Lt. Hiram Brewton. Brewton said Gentile was not exercising any police powers when he shot the man.

Gentile, who is 38, has been a police officer for 14 years, nine of them as a police spokesman.