A former D.C. police vice officer was sentenced yesterday to three to nine years in prison for obstructing justice and other crimes stemming from his return of a confiscated truck to a suspected drug dealer.

Wallace S. Najiy II, 37, tried to link his actions to sloppy paperwork, and he said he didn't intend to commit any crimes. But prosecutors convinced a jury in U.S. District Court that he deliberately gave favorable treatment to the suspect and pocketed $500 in return.

U.S. District Judge Thomas F. Hogan said Najiy's conduct could have a "ripple effect" because juries are increasingly skeptical about police testimony, even when the evidence is strong, because officers such as Najiy have "broken their oath."

Najiy was convicted in July of 10 felonies stemming from the officer's arrest in September 1995 of Gregory D. White on Georgia Avenue NW. After finding crack cocaine in White's truck, Najiy seized the drugs and vehicle. The truck was to be kept for forfeiture proceedings.

White, who pleaded guilty in the drug case, testified at Najiy's trial that he dealt with the officer through private investigator Clement F. Brown. White testified that Brown bragged about his ties to Najiy and said he could get matters "squared away" in return for money. White said that he gave Brown checks totaling $2,800 and some cash and that he got back the truck and a ring taken by Najiy during the arrest.

Brown testified that he gave Najiy $500. Brown, 64, pleaded guilty this year to a charge of aiding and abetting in the bribery of a public official and is awaiting sentencing.

Prosecutors said Najiy forged several official police documents. They also accused him of covering up the discovery of additional drugs in White's truck and lying to police officials.

Najiy, who joined the police department in 1988, was placed on administrative leave in February 1996. He resigned in January.

Yesterday, Hogan ordered Najiy to reimburse the District $5,100 for White's vehicle.

Najiy was the second former D.C. officer to appear before Hogan for sentencing this week. On Tuesday, Hogan sentenced Yong Ahn, a former lieutenant, to four months in prison for taking $8,000 in bribes from operators of illegal massage parlors.