Seattle police have launched an internal investigation into the alleged mishandling of dozens of drunken-driving cases by members of the department’s DUI Squad, prompting city attorneys to put some prosecutions on hold.

City Attorney Peter Holmes said in a statement that his criminal division will review current and past driving-under-the-influence (DUI) cases to determine whether they may be affected by the pending findings of the police investigation.

The investigation, disclosed by sources familiar with the matter and later confirmed by the department, is focused on accusations that arrest reports weren’t properly screened and approved by a sergeant in the DUI Squad, as required under department policy. The investigation has forced the department to pull all but one member of its five-member DUI Squad from the street and assign them to desk duties, according to police.

Other officers will be specially assigned to take over the nighttime squad’s regular DUI-enforcement duties during the investigation and patrol officers will continue to watch for impaired drivers, the department said.

The head of the Seattle police union, Sgt. Rich O’Neill, called the investigation an unfair reaction to a “”paperwork snafu.””

Among the allegations is that the sergeant, David A. Abe, a 32-year veteran, routinely did not report to work and approved DUI arrests by telephone, one source said.

A rubber stamp then was used by DUI officers to affix the sergeant’s name to reports, the source said.

The practice has been going on for about a year, another source said.

The Police Department is looking into the possibility that the sergeant’s name was put on reports without first contacting him, the department said.

Dozens of the squad’s current and past DUI cases might be compromised, said Kimberly Mills, spokeswoman for the City Attorney’s Office.

The investigation is the latest turmoil to hit the department, which is under review by the U.S. Department of Justice over allegations that officers used excessive force in several high-profile cases. The Justice Department, among other things, is looking at whether the Police Department has adequate procedures to ensure that front-line supervisors are performing their jobs.

In a written statement, the Police Department said Traffic Capt. Richard Belshay in mid-February began a review of some “”supervisory inconsistencies”” within the DUI Squad.

“”Upon closer examination, it was determined that administrative policy violations were in fact occurring,”” the statement said.

Police Chief John Diaz was briefed, and an assistant chief forwarded the information to the department’s Office of Professional Accountability, the statement said.

An investigation was opened March 8 into the conduct of the sergeant, according to the statement, which didn’t identify Abe by name.

The investigation then broadened into the conduct of three other officers assigned to the DUI Squad.

The sergeant and officers were administratively reassigned Wednesday, the department said. In addition to Abe, 56, they include a 23-year officer and two 12-year officers.

According to payroll records, Abe earned $106,000 in base pay and $39,000 in overtime in 2009. More recent figures were not available Monday.

One DUI Squad officer has not been named in the investigation and remains on duty, the statement said. Sources identified that officer as Eric Michl.

“”The scope of the investigation at this point focuses on the administrative policy violation of screening all arrests with a supervisor in person, which department policy requires,”” the statement said. “”This investigation is in its infancy. The scope may change as new information is developed.””

Whenever officers arrest or detain someone in any type of crime, the Seattle Police Department manual states that a sergeant “”shall be notified so that an in person review of the incident can occur … “”

Once at the scene or the precinct, supervisors are supposed to review the circumstances of the arrest and the condition of the suspect. The supervisor is supposed to evaluate the appropriateness of any allegation, sign off on any jail booking or release, and ensure evidence is properly collected and preserved, according to the manual.

“”It’s just an opportunity to have a second set of eyes look at the facts and circumstances of an arrest,”” said Sgt. Sean Whitcomb, the Police Department’s chief spokesman.

Seattle police commanders have met with Craig Sims, head of the city attorney’s criminal division, to advise him of the internal investigation, the Police Department statement said.

During the noon hour Monday, Sims briefed city attorneys on the matter, directing them that as of the 1:30 p.m. court docket to ask judges for continuances of DUI cases involving the three officers implicated in the investigation, according to the City’s Attorney’s Office.

The attorneys also were instructed not to agree to any guilty pleas in cases that involve the three officers.

Additionally, Sims contacted public-defense attorneys to notify them of the investigation.

Dan Donohoe, spokesman for the King County Prosecuting Attorney’s Office, said prosecutors are awaiting results of the police investigation to determine if they might have an impact on any felony DUI cases, including those involving injuries or deaths.

O’Neill, the Seattle Police Officers’ Guild president, said the lack of face-to-face screenings for DUI arrests doesn’t affect the validity of the police reports submitted to prosecutors.

“”There is video of all the arrests, and there’s evidence attached to each one,”” he said, noting the DUI Squad is staffed by highly trained officers.

“”This is the farthest thing from a scandal. This is an administrative, paperwork snafu, and these officers are the best in their field and it’s a shame if it’s characterized any other way,”” O’Neill said.

He said the Seattle department’s screening policy has not been enforced evenly for several years, but came to light when a new captain was assigned to oversee the unit and discovered the administrative violation.

O’Neill said the Police Department is the only local agency that requires face-to-face screenings for DUI arrests.

“”No one else requires this the way SPD says it’s supposed to be done,”” he said.

Sgt. John Urquhart of the King County Sheriff’s Office said sheriff’s deputies never have been required to screen DUI arrests with supervisors. Trooper Julie Startup, a spokeswoman for the State Patrol, said troopers aren’t required to screen DUI arrests with sergeants.

Unlike patrol officers assigned to specific areas of the city, members of the Seattle DUI Squad work citywide, requiring a sergeant to travel to disparate locations for screenings, O’Neill said.

The sergeant in question “”didn’t take a sick day in 30 years”” but recently has been dealing with “”extenuating circumstances,”” he said.

Both the sergeant and a family member have been dealing with “”extreme”” medical conditions, he said, and the sergeant has been taking sick time or working half shifts.

“”The supervisor involved has been going through hell, and I think some compassion is in order,”” O’Neill said.

“”I think what the investigation will reveal is that the arrests were preapproved, unless there was something out of the ordinary,”” O’Neill added, in which case a precinct sergeant could have been called to screen an arrest.

Seattle Times staff reporters Christine Clarridge and Jennifer Sullivan and news researcher Miyoko Wolf contributed to this story.