Unfortunately, you are not giving us any information about your character's build to provide any kind of real help. Are you a fighter already? A rouge that wants to get in the middle of things? Also, what exactly do you want/need the prestige class to do? Is it to show off how evil your character is? We don't know and can't direct you in any meaningful way until we do. In addition, how you do want to be deceptive?
With that out of the way, a lot of people feel that the Pathfinder prestige classes fill very niche positions (mostly tied tightly to their AP lore). If you DM allows 3rd party Pathfinder or better yet 3.5 content you'll have much better luck finding the exact prestige class for yourself. If neither of those are acceptable options, I would advise looking at the other classes (which I feel is a superior option to Pathfinder prestige classes). Off the bat I would suggest the hybrid class
Slayer. It comes with full BAB, a d10 HD and 6+Int mod skill points. In addition, it's Studied Target class feature is a weaker, but more versatile Favored Enemy.
If you can use 3.5 content you may wish to look at the following:
[1] Avenging Executioner - Complete Scoundrel: Many cool class features that scream this




er is evil.
[2] Battle Trickster - Complete Scoundrel: If you can find at least 4 skill tricks you like enough, can be a decent 3 lvl Prc. I'd check out
Group Fake-out,
Timely Misdirection,
Mosquito's Bite and
Spot the weak point
[3] Dread Commando - Heroes of Battle: Allows for melee characters who wears medium or heavy armor to participate in stealthy antics.
[4] Disciple of Baalzebul - Book of Vile Darkness: More rogue than warror, but contains a plethora deception bases class features. You'll need to work with the DM to rework the fluff though.
Deceptive Feats (pathfinder only) you may wish to look at:
Fox Style,
Incite Paranoia,
Wave Strike,
Disengaging Feint,
Disengaging Flourish,
Disengaging Shot,
Improved Dirty Trick,
Greater Dirty Trick,
Master Dirty Trick,
Quick Dirty Trick,
But a Scratch,
Misdirection Tactics,
Sliding Dash,
Deceptive Exchange,
Blustering Bluff,
Feign Curse and
Lifeless Gaze