Police have interviewed a person under caution following the alleged racial abuse of Raheem Sterling during Manchester City's defeat at Chelsea.
The incident involving the 24-year-old occurred during City's 2-0 loss at Stamford Bridge on 8 December.
Officers from the Metropolitan Police are reviewing CCTV footage to determine whether any offences were committed.
They are in possession of the details of those reportedly involved, but no arrests have been made.
Chelsea have suspended four people from attending matches while investigations take place.
The club said in a statement they were "fully supporting" police enquiries and any evidence of racist behaviour will result in "severe sanctions, including bans".
Following the incident, Sterling posted on Instagram saying newspapers are helping to "fuel racism" by the ways in which they portray young black footballers.
The England forward said he "had to laugh" when he heard the alleged racist remarks because he expects "no better".
"All I have to say is have a second thought about fair publicity and give all players an equal chance," he added.
One of the fans who has been suspended by Chelsea told the Daily Mail earlier this month that, although he swore, he used the word 'Manc' rather than 'black'.
"I'm deeply ashamed by my own behaviour," he said. "I want to apologise unreservedly to Raheem and hope he can be a better man than I am by accepting it.
"Even if it wasn't racist, it's not right what I said. Even the swearing is bad - but I got carried away. I was completely out of order."