Cadillac Repair: 2003 CTS..Key Locked in Ignition, accurate diagnosis, lock cylinder

Question
My Key is locked in Ignition and wont come out. It wont start the car the either.  I took it to a mechanic and he said that it had to do with the antitheft computer...for some reason it wasnt recgonizing the key and must be replaced...what does the antitheft computer cost and does this sound like an accurate diagnosis?..the car gets a reading when we turn the key...the lights come on and stuff works...car just doesnt start!!!

Answer
If you cannot remove the ignition key from the lock cylinder on the steering column and it is stuck in the lock, You have a problem with the lock on the steering column.

If you are mechanicaly inclined or know of someone who is, You will need a DIGITAL MULTIMETER, Simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.