CHICAGO — Jussie Smollett, upset by his salary and seeking publicity, staged a fake assault a week after writing himself a threatening letter, the Chicago police said Thursday after the “Empire” actor surrendered to face a felony charge of filing a false police report.

The Chicago Police Superintendent Eddie T. Johnson, visibly angry at a morning news conference, said Mr. Smollett had taken advantage of the pain and anger of racism, draining resources that could have been used to investigate other crimes for which people were actually suffering.

“I just wish that the families of gun violence in this city got this much attention,” he said, referring to the news media.

At an afternoon bail hearing, a judge set Mr. Smollett’s bond at $100,000. He was released late Thursday afternoon after posting bond and returned to the “Empire” set in Chicago where the show is being shot.

In Thursday’s proceedings, members of Mr. Smollett’s family were in the courtroom with him as the judge, John Fitzgerald Lyke Jr., said that he found the investigators’ account of the incident disturbing, particularly the assertion that Mr. Smollett had used a rope around his neck to heighten outrage.

“We live in a country where you are presumed innocent,” the judge said. “However, if these allegations are true, I find them utterly outrageous. Especially the violent, despicable use of a noose, which conjures such evil in our country.”

Mr. Smollett, wearing a black puffer jacket, did not react, though occasionally he whispered to his legal team during the 25-minute proceeding. One of the lawyers, Jack Prior, agreed that the police account was outrageous, but he said it also was not true.

“He wants nothing more than to clear his name,” Mr. Prior said of his client.

The police say Mr. Smollett hired two brothers to carry out the assault and paid them $3,500. They have a copy of the check used to pay them, the police said. Also recovered, they said, were phone records that showed Mr. Smollett speaking to the brothers an hour before the incident took place, and then an hour after.

In a document prepared for the bail hearing, prosecutors said they had video of the brothers at the scene, text messages they shared with Mr. Smollett and their testimony as to how Mr. Smollett had recruited them for the plan. He even had them visit the scene of what investigators contend was the fake attack, a spot near his home, on an earlier night to prepare, prosecutors said.

But, the prosecutor’s document said, a video camera at the spot that Mr. Smollett had hoped would capture a phony attack was pointed in the wrong direction.

Superintendent Johnson declined to indicate why investigators now believe that Mr. Smollett had also played the chief role in mailing himself a threatening letter. The letter, which arrived a week before the reported assault, contained a white powder (crushed ibuprofen) and a sketch of what appeared to be a man being hanged and phrases, including “You will die.” The return address said “MAGA,” a reference to a slogan from the Trump campaign.

Mr. Johnson referred further comment about the letter to the F.B.I., which is investigating that part of the case. The agency declined to comment.

The actor, who surrendered to the authorities on Thursday morning, has insisted the attack occurred and that he has not done anything wrong. The felony disorderly conduct charge he faces carries a maximum sentence of three years in prison.

After his arrest, the reversal in public opinion for Mr. Smollett was quick and damaging. The report of the attack spurred a national outpouring of support, including from Democratic presidential candidates and President Trump, who called the incident “horrible.”

[Read more about Jussie Smollett’s life and career.]

On Thursday, some of the celebrities who had initially supported Mr. Smollett, began taking down their social media posts from the aftermath of the attack.

Fox, the network that airs “Empire,” released a statement Thursday saying it was evaluating the situation and the network’s options. “We understand the seriousness of this matter and we respect the legal process,” the statement said. Network executives later confirmed that among those options was that he return to the set and resume work as Jamal Lyon.

Mr. Smollett’s official salary has not been made public, but he reportedly earned between $65,000 and $100,000 an episode on “Empire.” It was not immediately apparent whether he has had any clashes with executives at Fox, who, as recently as Wednesday, issued a statement highly supportive of the actor, calling him a “consummate professional.”

At their news conference and the bail hearing, police and prosecutors unveiled much of what they had uncovered about the reported attack. Mr. Smollett, 36, who is black and openly gay, had told the police that at roughly 2 a.m. on Jan. 29, two masked men attacked him on the 300 block of Lower East North Water Street in downtown Chicago. He said his assailants directed homophobic and racial slurs at him, put a rope around his neck and poured a chemical substance on him. Mr. Smollett said the assault occurred after he went to pick up food.

A detective commander, Edward Wodnicki, said at the news conference that investigators interviewed Mr. Smollett at Northwestern Memorial Hospital and found he had scratches on his face, some bruising, but no serious injuries.

The investigators approached the case as a possible hate crime, but had difficulty finding evidence to match Mr. Smollett’s account. The attack itself was not visible on surveillance cameras.