A former Philadelphia homicide detective was arrested Tuesday and accused of grooming and sexually assaulting male witnesses during criminal investigations, then intimidating them to keep them silent — part of what prosecutors concluded was a pattern of misconduct during nearly a decade in one of the Police Department’s most prestigious units.

The accusations against Philip Nordo, 52, who was fired in 2017 after 20 years on the force, were unveiled in a grand jury presentment following a long-running probe into the ex-detective’s conduct. The charges include multiple counts each of rape, involuntary deviate sexual intercourse, and sexual assault.

Some of the allegations were redacted, with entire pages of the 38-page document blacked out. Names and details of those allegedly raped by Nordo were among the redactions.

Still, according to the presentment, the grand jury found that Nordo “repeatedly contacted young men that he sought to groom,” and used threats and flattery to “make the targets of his advances more susceptible to his sexually assaultive and/or coercive behavior.” Prosecutors said Nordo’s tactics included threatening to arrest or jail suspects without probable cause, fraudulently steering reward money their way, and projecting his dominance — sometimes by displaying his firearm, other times by targeting handcuffed prisoners.

The abuse occurred in interrogation rooms and prison visiting rooms, the document says, adding that Nordo allegedly went out of his way to find potential victims, either by asking prisoners about “homosexual inmates” who might soon be released, or by volunteering to transport inmates and witnesses for other detectives.

The allegations are likely to not only serve as the backbone of a criminal prosecution against a once-prolific homicide detective, but could imperil an untold number of convictions that Nordo helped secure.

Nordo was arraigned Tuesday and ordered held without bail over the objection of his attorney, Michael T. van der Veen, who said charging guidelines called for bail of $10,000.

After the hearing, van der Veen said Nordo maintains his innocence and intends to fight the case. Van der Veen said that although he personally supports many of the actions taken by District Attorney Larry Krasner over the past year, he believes that this prosecution was motivated by unspecified “political forces."

Van der Veen entered the case after the police union declined to provide Nordo legal representation. John McNesby, president of the union, Fraternal Order of Police Lodge 5, said Tuesday that he had not yet read the presentment. Asked how Nordo could have committed such crimes in connection with his official duties, McNesby said that he had “no idea” and that he had never before heard allegations like this.

Police Commissioner Richard Ross said in an interview Tuesday that he was “deeply disturbed” by the allegations, but that “I have nothing from our investigation to suggest [the Police Department] has to be concerned” about others assisting Nordo or covering up his alleged crimes.

“It is not systemic, but I don’t get a lot of solace over that,” said Ross, who said the behavior described in the presentment was “absolutely sickening.”

Krasner, speaking after an unrelated news conference Tuesday at City Hall, declined to elaborate on specific allegations included in the document.

Even before charges were filed, Krasner’s office had been quietly dismissing or altering cases connected to Nordo, the Inquirer reported last month. Much of the recent activity had been conducted under seal.

Nordo joined the Police Department in 1997, the presentment says. A 1999 Daily News article described him as a third-generation cop who was married with two children. He became a detective in 2002 and joined the Homicide Unit in 2009, the presentment says, and became known as a productive investigator often assigned complex or challenging cases.

It was not clear Tuesday how many prosecutions Nordo’s arrest might impact. Gary S. Server, whose client Brandon Meade was arrested by Nordo, said he is reviewing Meade’s murder case to determine Nordo’s full role. Meade is serving a life sentence after being convicted of murdering his girlfriend, a 21-year-old Temple University student, then staging the scene to look like a suicide.

“It looks like a lot, if not all of his cases, are going back for review,” said Server.

The decision to charge Nordo serves as another example of how Krasner — formerly a defense attorney who specialized in lawsuits targeting police misconduct — has been willing to investigate and prosecute law enforcers in ways that his predecessors did not. Last year, for the first time in two decades, Krasner charged another former officer with murder over an on-duty shooting, a decision that drew immediate condemnation from the police officers’ union.

In the only specific instance of assault left unredacted in the presentment, prosecutors said that while Nordo was a member of the East Detective Division in 2005, he directed a man during questioning to masturbate, then touched and kissed the man during the act. The man, who remained in custody after the assault, reported it to police the next day, the document says.

Investigators later found physical evidence to support the man’s assertion, the document says, but Nordo remained on the force.

According to the presentment, the man assaulted by Nordo was killed in 2015, and the case was never solved. It does not identify the man or say when or how he was slain.

The rest of the accusations against Nordo are blacked out throughout the document, but other counts he faces include stalking, official oppression, and sexual assault.

Nordo’s downfall began in April 2017, when a defense attorney in a pending murder case discovered that the detective had been improperly placing money in the account of an imprisoned witness. The attorney, Robert Gamburg, said the transactions were never disclosed to him and argued that the case against his client, Darnell Powell, should be dropped.

Four months later, Nordo was fired for departmental violations including "knowingly and intentionally associating, fraternizing, or socializing" with people connected to criminal conduct, police said at the time. They did not offer further details.

In July 2018, Common Pleas Court Judge Diana L. Anhalt dismissed the case against Powell over what she called Nordo’s “outrageous” misconduct. In addition to the undisclosed payments, Anhalt said, it seemed to her as if Nordo had drafted a statement for another man and simply gotten him to agree with it, and she questioned why a different witness was recorded telling Nordo on the phone: “I love you.”

Two weeks after that decision, another man charged in the same homicide — who had already pleaded guilty and faced the potential of decades behind bars — was instead granted immediate parole and given five years’ probation.

Then, two more cases connected to Nordo were altered under seal.

In August 2018, Common Pleas Court Judge Charles Ehrlich agreed to drop the prison sentence in a gun and drug case and place the defendant, Adriel Alverado, on eight years’ probation instead. Nordo’s role in that case was not immediately clear, but Alverado referenced his name in appeal documents.

In December 2018, Common Pleas Court Judge Steven Geroff agreed behind closed doors to vacate the third-degree murder conviction of Jamaal Simmons. Geroff did not explain his decision in public; the District Attorney’s Office declined to try Simmons again.

Simmons, who was arrested in 2009 and was convicted and sentenced to 15 to 30 years in prison, had maintained he was innocent.

Staff writer Mark Fazlollah contributed to this article.