Is my 10 year old son a thief?

my 10 year old son has been caught stealing several times in the last 3 or 4 years. now it is getting worse. at first it was just a handful of change. then it was a $1 here and $2 there. this morning he was caught with $15. my husband have been noticing money coming up missing lately, but have just been shoving it off as nothing. but now we are begining to think it was our son taking it. we have tought him that stealing is wrong no matter what was taken. we have punished him in the past, but it obviously has not done any good. i just don't know what to do. i am afraid that if something is not done soon he will end up in jail. my son also has some anger problems. we have tried to put him in counseling, but his grades in school dropped drasticly. what can i do to help him? i am at a loss as to what to do.