Now we know why Lindsay Lohan's 2007 DUI case may have plea bargained so quickly -- the cop who took custody of the cocaine mistook it for a breath mint and threw it in the trash.
Pretty incredible, but according to the Santa Monica Police report -- obtained by TMZ -- the officer "discovered a folded Clinique sun care card with an unknown substance caked on to the surface of the card in Lohan's right rear pocket."
The report goes on: "Some of the white substance fell to the floor. I used my foot to see what had fell but thought nothing of it. I did not recognize the substance attached to the card and initially thought the substance was a wet crushed breath mint."
And now it gets good: "I put the card into the jail trash can next to the booking windows. I was looking at the floor and began to recognize the substance as resembling powder cocaine. I then recovered the card from the trash."
The cop says the coke was in the trash for about 2 minutes. He put the card in an evidence envelope, then scooped up the coke that had fallen to the floor and placed it in a separate evidence envelope.
In short -- EVIDENCE CONTAMINATION!!!
Lindsay ended up with a sweet deal and spent 84 minutes in jail ... for a drunken, cocaine-fueled chase on Pacific Coast Highway. Nice deal if you can get it.