1/14 2:57 PM PT -- Memphis police have a lead in the Big Jook shooting ... posting photos of a white Ford Explorer they say may have carried the rapper's killers.

They're asking the public for help identifying the car and are offering a $4,000 reward for information.

Yo Gotti's brother, Anthony 'Big Jook' Mims, was shot and killed this weekend ... TMZ has confirmed.

Sources with direct knowledge tell us the rapper's older sibling was gunned down Saturday in Memphis on near Winchester Road. Per reports, this murder took place after he'd attended a funeral service in the area.

There are photos and videos circulating online that purportedly show Jook bleeding on the ground with people attending to him. The exact details of the shooting are unclear at this point ... but Jook is confirmed dead.

Big Jook was incredibly close to his famous brother ... he appears to officially be affiliated with Gotti's label Collective Music Group -- promoting artists under the imprint and appearing in music videos for them as well. Jook seemed to be more so on the business side.

It's sad that he happened to be killed during a time of mourning -- something he alluded to in one of his last IG Stories Saturday ... where he was honoring a fallen relative.

Unclear if Gotti himself was with Jook during the killing -- he hasn't addressed his brother's murder just yet either. Another element to this is the possibility that this might be related to the murder of Young Dolph in 2021 ... at least that's the speculation online anyway.

As we reported ... cops rushed to Gotti's Memphis restaurant shortly after the young rapper was shot down himself outside of a cookie store -- this out of fear of possible retaliation.

It's no secret Dolph and Gotti had beef ... and now, many suspect this might be connected. Also worth noting -- the location of Jook's murder is not far from Gotti's establishment ... in fact, it's on the same block. This is also not very far from where Dolph's murder took place.

We've reached out to Gotti's camp for comment ... so far, no word back.