Boxing star Jermall Charlo is a suspect in a police investigation of a brutal assault that allegedly took place over the weekend ... TMZ Sports has learned.
Cops in Fort Bend County, Texas tell us they responded to a Missouri City residence at around 10 PM on May 23 ... initially for a welfare check.
But, officers say when they arrived ... someone reported there was an aggravated assault causing serious bodily injury during a party at the residence -- and they launched an investigation.
Cops are mum on the details of the allegations -- we're working on it -- but they do say they have identified Charlo as a suspect in the case.
The 30-year-old WBC middleweight champ has NOT been arrested at this time.
Charlo is one of boxing's biggest suspertars ... he's 30-0 in his pro career with 22 knockouts.
We've reached out to Jermall and his camp for comment ... but so far, no word back yet.