Chicago police have released two Nigerian brothers arrested in connection with the alleged assault on Empire TV series actor Jussie Smollett and said they have new evidence to investigate as a result of questioning them.

“The individuals questioned by police in the Empire case have now been released without charging and detectives have additional investigative work to complete,” Chicago police spokesman Anthony Guglielmi said in a statement.

He gave no details of the new evidence. The police department said the individuals are no longer classified as suspects.

The brothers, one of whom worked on Empire, were intercepted on Wednesday as they arrived back at Chicago’s O’Hare airport from Nigeria. Police have also confirmed that they searched the pair’s house on Thursday under a warrant.

Their arrest added a twist in the narrative of the reported attack on Smollett on 29 January. It came only a day after the actor and R&B singer had given his first detailed account to ABC News in which he said he had been set upon by two white assailants hurling racial and homophobic insults at him and slinging a noose around his neck.

In an emotional interview with Good Morning America, Smollett said his attackers had shouted “This is Maga country!” – a reference to Donald Trump’s mantra “Make America Great Again”. He also said he believed he was targeted because of his frequent political criticism of the president.

Two men were captured on surveillance camera in the vicinity of the reported assault on Smollett.

On Thursday, in a further twist, Guglielmi took the unusual step of publicly rebuffing speculation in the Chicago media that police were investigating whether the incident was in fact staged. In a tweet, he said: “Media reports about the Empire incident being a hoax are unconfirmed by case detectives.”

Media reports anout the Empire incident being a hoax are unconfirmed by case detectives. Supt Eddie Johnson has contacted @ABC7Chicago to state on the record that we have no evidence to support their reporting and their supposed CPD sources are uninformed and inaccurate. pic.twitter.com/iSO5YFv452 — Anthony Guglielmi (@AJGuglielmi) February 15, 2019

Smollett’s account of events has been challenged by doubters on social media who have questioned why he initially resisted handing over his cell phone to police and why later he gave them only a heavily redacted record of his calls around the time of the incident.

The actor defended himself on ABC News, saying he had been hesitant because he wanted to protect the privacy of his partner, family and fellow Empire cast members.

“It feels like if I had said it was a Muslim or a Mexican or someone black, I feel like the doubters would have supported me a lot more,” he said.