What happened to the OP? There's a world of difference between getting arrested, and getting charged. I have a hard time believing he'd actually been charged when it's so easy to prove he's 100% clear.
You're both wrong, according to
Snopes.
This is the version I have also been told is the origin, that being someone who Cops, or Copper, for those who arrest people and seize things.
Etymology 1
From Middle English coppe, from Old English *coppe, as in ātorcoppe (“spider”, literally “venom head”), from Old English copp (“top, summit, head”), from Proto-Germanic *kuppaz (“vault, round vessel, head”), from Proto-Indo-European *gū- (“to bend, curve”). Cognate with Middle Dutch koppe, kobbe (“spider”). More at cobweb.
Noun
cop (plural cops)
(obsolete) A spider.
Etymology 2
Possibly from Middle French capere (“to capture”), from Latin capere (“to seize, to grasp”); or possibly from Dutch kapen (“to steal”), from West Frisian kāpia (“to take away”), from Old Frisian kapia, to buy.
Verb
cop (third-person singular simple present cops, present participle copping, simple past and past participle copped)
(transitive, formerly dialect, now informal) to obtain, to purchase (as in drugs), to get hold of, to take
(transitive) to (be forced to) take; to receive; to shoulder; to bear, especially blame or punishment for a particular instance of wrongdoing.
When caught, he would often cop a vicious blow from his father
(transitive) to steal
(transitive) to adopt
No need to cop an attitude with me, junior.
(intransitive, usually with "to") (slang) to admit, especially to a crime.
I already copped to the murder. What else do you want from me?
Harold copped to being known as "Dirty Harry".
and
http://www.etymonline.com/index.php?term=cop
cop - 1704, northern British dialect, "to seize, to catch," perhaps ultimately from M.Fr. caper "seize, to take," from L. capere "to take" (see capable); or from Du. kapen "to take," from O.Fris. capia "to buy," which is related to O.E. ceapian (see cheap). Related: Copped; copping.