Kurt Zouma could be charged 'within days' by the RSPCA after his cats were rescued by the charity.
The West Ham defender, 27, was filmed kicking and slapping the two pets in a shocking video published on Monday evening.
According to reports, Zouma has already been questioned by the charity's officers and is unlikely to receive his two cats back.
If prosecuted or convicted, he could face a ban from owning animals or a jail sentence, although the latter is unlikely.
West Ham have fined the Premier League player two weeks' wages - around £250,000 - but have stopped short of formally suspending him.
"The RSPCA has been working at an incredible pace - even before video of Zouma’s cat abuse went viral," a source told The Sun.
"There is big pressure for them to be taking decisive action after police handed them the lead on the investigation.
“If they deem it severe enough, Zouma could be charged as quickly as next week.
"There’s a lot of public anger over what happened, and quite rightly, but the investigation needs to be done to the book."
An RSPCA spokesperson said on Thursday evening: "Two cats are in our care, have been seen by a vet and are being well looked after.
"They will remain in our care while the investigation continues and are not available for rehoming, although we have lots of beautiful cats who are looking for new homes: www.rspca.org.uk/findapet.
"We understand the high level of interest in this incident and can reassure you that our experienced officers are carrying out a full and thorough investigation.
"Due to the fact that this is a live investigation, we are limited in what we can say, however we will provide updates when we are able."
West Ham's most recent statement on the matter was released on Wednesday.
"West Ham United can confirm that the club is supporting an RSPCA investigation into the actions of Kurt Zouma in the video circulated online this week," said the Premier League side.
"Kurt and the club are cooperating fully with the investigation and the player has willingly complied with the steps taken in the initial stage of the process, including delivering his family's two cats to the RSPCA for assessment.
"Kurt is extremely remorseful and, like everyone at the club, fully understands the depth of feeling surrounding the incident and the need for action to be taken.
"Separate to the RSPCA's investigation and pending further sanction once the outcome of that process is determined, West Ham United can confirm that Kurt Zouma has been fined the maximum amount possible following his actions in the video that circulated.
"The player has immediately accepted the fine, which will be donated to animal welfare charities. West Ham United would like to reiterate our condemnation of Kurt's actions and make it clear that the matter continues to be handled with the utmost seriousness.
"However, we believe it is now important to allow the RSPCA to conduct their investigation in a fair and thorough manner and will be making no further comment at this stage."
Zouma apologised for the incident when the video emerged, telling The Sun: "I want to apologise for my actions. There are no excuses for my behaviour, which I sincerely regret.
"I also want to say how deeply sorry I am to anyone who was upset by the video. I would like to assure everyone that our two cats are perfectly fine and healthy.
"They are loved and cherished by our entire family, and this behaviour was an isolated incident that will not happen again."
