A Seattle police sergeant who built a stellar career before an internal investigation found misconduct in his supervision of drunken-driving arrests has retired after being told the department planned to fire him.

Sgt. David Abe's retirement was disclosed by sources briefed on the matter. A Seattle police spokesman, Sgt. Sean Whitcomb, confirmed Monday that Abe retired Thursday after an investigation by the department's Office of Professional Accountability (OPA) led to a recommendation that he be demoted to the rank of officer, then fired.

The department hasn't released the findings of its internal investigation of Abe, a veteran of nearly 33 years who supervised officers in the unit that enforces driving-under-the-influence (DUI) laws.

But the investigation has focused on allegations that Abe, 57, repeatedly failed to report to work and provided a rubber stamp to officers to affix his approval on their arrest reports, according to sources.

One high-level source said Abe had a good record during most of his career but displayed a "marked decline in performance" tied to health problems, a family illness and unhappiness over his assignment, for a second time, to the DUI Unit last year.

Abe was to meet with Police Chief John Diaz to discuss the proposed discipline but opted to retire, another source said.

Last year, Abe earned $108,034 in regular pay and $49,691 in overtime, according to city payroll records.

Throughout his career, Abe received numerous commendations for his work, notably for perfect attendance during a number of years, including a period from December 1978 to February 1988 in which he didn't take a day off for illness or injury, department records show.

His only listed discipline occurred last year, when he was reprimanded over the way a driver's license was returned to a citizen.

Abe and three officers became the subjects of internal investigations in March after an audit found dozens of DUI cases had been mishandled.

In a June 22 report, the department found that two officers in the DUI Unit routinely used a signature stamp without having a sergeant approve their arrests as required by department policy.

The third officer, John Velliquette Jr., put written statements in his reports attesting that his arrests had been approved by a sergeant even though no review had occurred, the report said.

The three officers were cleared of misconduct allegations involving honesty and arrest procedures after the OPA heard testimony that the practice preapproving arrests had been going on for 20 to 25 years. Most area law-enforcement agencies do not require DUI arrest screening because suspects are generally released after processing, the OPA noted.

Although the allegations were not upheld, the three officers were ordered to undergo supervisory counseling and training for violating department policy.

Velliquette, in an April interview with a defense attorney representing a DUI defendant, said Abe's brother was dying of cancer at the time of the events under investigation, and that Abe was suffering from his own health problems, according to court documents.

Abe also "wasn't happy" when he was assigned to the DUI Unit in March 2010, Velliquette said, characterizing Abe's supervision as "not much."

Asked if Abe had screened arrests in person, Velliquette stated "not that I recall" and related that, in his opinion, supervision of the DUI officers had been lacking.

His statements were used by defense attorneys in another case, who sought dismissal of a DUI charge against their client or suppression of Velliquette's testimony.

A Seattle Municipal Court judge declined the requests Sept. 1 but said Velliquette could be cross-examined by the defense about his false statement that a sergeant had approved the arrest.

Information from Seattle Times archives is included in this story.

Steve Miletich: 206-464-3302 or smiletich@seattletimes.com