LINDEN — The city's police department would have been required to inform the county prosecutor and conduct an internal investigation both times Officer Pedro Abad was charged with drunken driving, according to the department's policies. e

Authorities are investigating Abad's employment and driving history, after

two past charges of driving while intoxicated came to light

in the days following the March 20 Staten Island crash. Abad's Honda Civic hit a tractor-trailer head-on, killing two people, including a fellow officer.

Department officials have declined to comment on what was known about Abad's driving record or how his past two drunken driving charges were handled, but internal affairs policies shed some light on what the response may have included.

The policies, obtained by NJ Advance Media through a public records request, require any officer or police department employee charged with driving while intoxicated to immediately notify the on-duty shift commander at police headquarters.

This procedure also applies to officers charged with indictable offenses, drug crimes or domestic violence.

The shift commander must then "make a prompt notification" to the internal affairs supervisor and fill out a written report. The internal affairs supervisor, in turn, is responsible for immediately contacting the Union County Prosecutor's Office.

An investigation into whether the department properly followed procedures after Abad's arrests

was transferred last week from Union County to the Middlesex County Prosecutor's Office

, a move officials said was to avoid the appearance of any conflicts of interest.

"We welcome any investigation into our department and the handling of internal matters involving our personnel," Capt. James Sarnicki, the public information officer for Linden police, said after the change of prosecutors was announced.

For motor vehicle summonses other than parking offenses, the police department policy requires officers to inform the internal affairs unit on the next regular business day, and staff there will determine whether to alert the prosecutor.

Abad's driving record

lists eight accidents in the past decade

, including seven while he was a member of the force. Abad was charged with DUI in two of those crashes, one in Rahway in 2013 and one in Roselle in 2011,

led to drunken-driving charges

, though the

Roselle charges were later dismissed

.

Linden police issued Abad a summons for careless driving in August 2012, after he

rear-ended a car stopped at a red light and told responding officers he'd been looking at his phone

.

Otherwise, Abad was not charged or cited in any of the accidents on his record.

When Linden officers are charged or involved in civil matters, the department's internal affairs unit tracks the proceedings, according to the policies.

Internal affairs policies give supervisors, command officers and the police chief authority to immediately suspend an officer from duty if the officer is formally charged with a first-, second- or third-degree crime. As municipal offenses,

drunken driving charges do not rise to that level

.

Officers can also be immediately suspended if charged with a crime of any degree or a disorderly persons offense while on duty, or a crime related to their job. Other reasons for immediate suspension include if officers are "unfit for duty"; if their remaining on the job creates a hazard to any person; or if a suspension would be "necessary to maintain safety, health, order or effective direction of public services."

The department has not disclosed whether Abad was suspended, placed on desk duty or otherwise had his workload and responsibilities modified during the period when his driver's license was suspended and an ignition-interlock device was installed on his personal car.

Sarnicki previously said in a statement that the department would not necessarily be notified of an officer's traffic accidents unless charges were filed, and any prior accidents or charges would be part of an internal record that would not be released. Echoing the internal affairs policies, he said an officer who was charged would have to notify the department and an internal investigation will take place.

The department's policies define internal affairs investigations as confidential.

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Katie Lannan may be reached at klannan@njadvancemedia.com. Follow her on Twitter @katielannan. Find NJ.com on Facebook.