Memphis DJ 'Slick Rick' Found Decapitated at Home ... Police Investigating

10:08 AM PT -- Memphis PD says a cause of death for Rick Buchanan has yet to be determined, and more interestingly ... that there's no sign of foul play in terms of how he died. Of course, they say they're still investigating.

A local DJ in Memphis, who just so happens to have the same moniker as a very famous rapper, appears to have been murdered in gruesome fashion ... via beheading.

Rick Buchanan -- otherwise known as "Slick Rick" in the area, no affiliation to THE Slick Rick -- was found dead Wednesday by his brother -- who told FOX13 reporter Walter Murphy that he walked into his sibling's home and discovered he'd been decapitated.

Buchanan's sibling, John, relayed the horrifying incident to the outlet, saying ... "I walked in and found him, and I just called 911." He goes on to describe exactly how he found him.

John adds, "I thought his coat was up over his head like it was cold or something. I ran out and then I ran back in. And, then I realized it was something worse." Rick's brother goes on to explain Rick was still holding his keys in this state, and that his pants were pulled down. He also says his back door was ajar ... so, to say this is suspicious is an understatement.

One other thing ... Rick was actually shot during a robbery in Memphis back in 2014, which he survived at the time -- but John says he was never the same after that.

He says it had become hard for Rick to find work, and that he became a bit of a recluse -- this despite being a huge personality known in the community for years ... who was big on performing. Now, John and the extended family say they're trying to piece things together on what exactly happened to Rick -- and, of course, making funeral arrangements, etc.

The obvious question ... what are cops saying? FOX13 cites Memphis PD as only saying they're investigating. On its face, it sounds like an outright slaughter and butchering.