James Holmes -- Possible Prostitute Connection

TMZ has obtained information which may show Colorado shooter James Holmes was involved with multiple prostitutes in the months before the movie theater attack.

Holmes was no stranger to sex web sites ... and sources tell us he also frequented a message board where potential johns posted reviews for hookers in the Colorado area.

We found the message board ... and discovered several posts written under James' supposed screen name ... in which he details multiple sexual encounters with different prostitutes.

TMZ spoke to three of the women Holmes supposedly reviewed. Hooker #1 told us she meets with lots of men and couldn't confirm she ever did business with James.

Hooker #2 said Holmes "looked very familiar" but couldn't say for certain if he was a client.

But Hooker #3 was POSITIVE she had met up with Holmes ... not once, but twice ... as recently as August 2011.

The woman, who goes by the name "Tiffany" -- tells TMZ ... "I had no issues with him … he was really nice.”

She added, "He felt bad that I wasn’t getting more customers while in Colorado, so he called a few days later and we met up again.”