Chicago police say that US actor Jussie Smollett is suspected of filing a false police report.
The Empire star had said he was subjected to a homophobic and racist physical attack by two men in January.
Doubt was later cast on his account after US media reported that police believed he may have paid two Nigerian brothers to stage the attack.
On Wednesday a police spokesman confirmed they were presenting evidence about the actor to a Grand Jury.
“Jussie Smollett is now officially classified as a suspect in a criminal investigation by Chicago Police for filing a false police report (Class 4 felony),” the spokesman, Anthony Guglielmi, said in a tweet.
Mr Smollett’s lawyers have not yet responded to the development.
His lawyers have previously issued a strong denial of allegations that he had faked the attack, saying the actor had “been further victimised by claims… that Jussie played a role in his own attack. Nothing is further from the truth and anyone claiming otherwise is lying”.
Earlier on Wednesday, CBS Chicago obtained footage which appeared to show the two brothers buying materials, including ski masks, that had allegedly been worn by the actor’s attackers.
The brothers, Ola and Abel Osundairo, left the US after the alleged attack and were arrested on their return last week. They were later released and are said to be co-operating with the investigation.
One of the brothers is Smollett’s personal trainer and both have worked as extras on Empire.
What did Smollett say happened?
He said he had gone out to buy food late at night when two white men hurled racial and homophobic insults at him, punched him, poured a chemical substance over him and put a rope around his neck.
“This is Maga country,” he says they told him, referring to President Donald Trump’s Make America Great Again slogan.
The actor said he had been “forever changed” by the incident.
The incident led to an outpouring of support for Smollett from stars including Oscar winner Viola Davis and supermodel Naomi Campbell.