NEWARK — An Essex County Sheriff's officer was charged with sexual assault and official misconduct after coercing a prostitute into sex by threatening her with arrest, according to court documents.

A criminal complaint filed in Essex County Superior Court claims Dinis Oliveira used both his badge and a handgun to intimidate the 31-year-old Newark woman during the Feb. 26 encounter.

Oliveira and the woman then engaged in both oral and vaginal sex, the complaint says.

According to law enforcement sources, Oliveira contacted the woman by phone after seeing an advertisement posted on Backpage.com, and arranged a meeting with her.

The victim reported the alleged assault to authorities two days later.

Sources said the woman presented authorities with a condom she claimed Oliveira used during the assault, and was taken to Newark Beth Israel Hospital to be examined. While at the hospital, she spotted Oliveira, who was there assisting a family member, and alerted police.

Oliveira, 31, turned himself in to the Essex County Prosecutor's Office on March 4. He was briefly held on $200,000 bail at the Essex County Correctional Facility following his arrest, but was released later the same day, according to sheriff's records.

He is charged with single counts of second-degree sexual assault, second-degree official misconduct and fourth-degree criminal coercion.

He was scheduled to be arraigned in Essex County Superior Court today, but the hearing was postponed. It is unclear if he has retained an attorney.

Essex County Sheriff Armando Fontoura said Oliveira had been a member of the department since June. He has been suspended without pay pending the outcome of his case.

Dan Ivers may be reached at divers@njadvancemedia.com. Follow him on Twitter at @DanIversNJ. Find NJ.com on Facebook.