One week after three off-duty Linden police officers were involved in a fatal car crash, there are questions regarding the driving history of the driver.

Linden Mayor Derek Armstead wants an internal investigation of the police department after discovering Officer Pedro Abad, the driver in the crash that killed another Linden police officer and his friend, had two DUI arrests since 2011 and has been involved in eight crashes since 2005.

"There are clearly some things in his past that have surfaced that are not pleasing," Mayor Armstead says.

Many have wondered why Abad wasn't fired from the force after either of his DUI arrests. However, attorney Kenneth Vercammen says a DUI isn't necessarily severe enough for immediate dismissal.

"Sometimes it can be up to the chief or public director to determine if they are going to give the person light duty," Vercammen says.

News 12 New Jersey has found that each police department has its own set of rules about officers convicted of DUIs.

Toxicology reports for Abad are still pending. No charges have been filed regarding the Staten Island crash.

Abad and Office Patrik Kudlac remain hospitalized.