LINDEN -- As former city officer Pedro Abad's drunk-driving case returns to court Monday, city officials have released details of decisions and timing surrounding his dismissal from the police department.

Abad is charged in the off-duty crash on March 20 in Staten Island in which fellow officer Frank Viggiano and Linden resident Joseph Rodriguez were killed and another Linden officer, Patrik Kudlac, was critical injured.

Abad, who was also critically injured in the crash, remained on the force for another six months, until September when he was suspended shortly after Staten Island authorities announced he had been indicted. He was unable to work during that six months because of his injuries, but remain on the force, according to the department.

Three months later, in early December, Linden police announced that Abad had been dismissed from the force retroactive to Aug. 13.

Linden had filed administrative charges against Abad in August, city attorney Daniel Antonelli told NJ Advance Media in the first comments made about the municipality's handling of the case.

Last August, Antonelli said, the city informed Abad that he faced administrative charges because he had used up all accrued sick time and other time off, and he was unable to perform his duties. Abad continues to receive treatment for injuries suffered in the crash.

Antonelli said Abad was officially dismissed Oct. 29, with the termination effective as of the date of the Aug. 13 administrative charges.

Labor attorneys familiar with law governing public employees say municipalities often will wait for a pending criminal investigation to be completed before taking disciplinary action.

"Six months does sound like a long time, but I'm not surprised," said Andrew Oddo, an Oradell attorney who has been dealing with public employee labor law for more than 15 years.

Waiting for the Staten Island District Attorney to file criminal charges against Abad gave Linden more leverage to support a suspension, Oddo said.

"It's possible they (Linden) didn't want to pull the trigger too early, until something as serious as an indictment comes down," he said.

State Civil Service regulations give employees rights to challenge any disciplinary action, such as being suspended without pay, Oddo said.

Linden may have been able to suspend Abad before the indictment, based on the allegations of the drunk-driving crash, said labor attorney Arthur Thibault, but the officer would then be entitled to a hearing where the city would have been required to prove the allegations.

"There's a lot of questions of what did Linden know and when did they know it," the Basking Ridge lawyer said. "If Linden doesn't have the proof, then their hands are tied."

Thibault questioned why Staten Island authorities waited so long to file charges.

"I can't understand why this thing was dragging," he said.

Antonelli said the municipality followed all the legal requirements.

"The city moved as expeditiously as it could under the law to remove Officer Abad," Antonelli said. He said Abad has not notified the city of any plans to appeal the charges.

Linden police, when asked about charges against Abad, have referred all questions to Antonelli. The Linden PBA representing city officers has previously declined to comment on the case.

Abad has pleaded not guilty to charges of aggravated vehicular homicide and manslaughter, as well as other allegations included in a 27-count indictment from the March 20 accident. Abad, Viggiano, Rodriguez and Kudlac had been at a Staten Island strip club, Curves, until the early morning hours of March 20. Shortly before 5 a.m., Abad was driving back to New Jersey when he made a wrong turn and drove the wrong way on a highway, crashing head-on into a tractor-trailer.

Abad is expected in Supreme Court in Staten Island on Monday for a hearing about tests done on his blood sample. His attorney, Mario Gallucci, has suggested that dancers at the club secretly drugged Abad with GHB to make him more willing to spend for drinks or give large tips.

Prior to the Staten Island accident, Abad had twice been charged with drunk-driving for accidents in Rahway and Roselle. The Roselle charge was dismissed after Abad's attorney failed to receive evidence from Roselle police, but Abad pleaded guilty to the charge from the Rahway accident.

Tom Haydon may be reached at thaydon@njadvancemedia.com. Follow him on Twitter @Tom_HaydonSL. Find NJ.com on Facebook.