As we reported, someone dumped a load of poop on Trump's star on the Hollywood Walk of fame. It's not vandalism -- because there was no damage -- but it would seem it's a violation of the L.A. Pooper Scooper ordinance ... HOWEVER, we've learned there's a twist.

Well, TMZ has cracked the case. Turns out Axl, an 18-month-old rescue, was walking on Hollywood Blvd. with his owner, James Hawkins, when nature called. Axl took a giant poop near Trump's star, and rather than picking it up, Hawkins decided it should adorn Trump's star.

James tells us he picked up the poop and placed it on 45's star. He took a photo to keep the memory alive. A short time later, James bagged the poop and left the scene of the crime.

James is a photographer from Rhode Island, who was in town on business. He tells us he's a democrat, and he's not a fan of Trump's ... in fact, he said he thinks Trump is "a piece of s**t," so James felt one good piece deserves another.

BTW ... it doesn't appear James violated the Pooper Scooper ordinance because he blue-bagged the excrement in short order.