A Crime Story (riddle)

[Ace Mercury]

Here's a reblog'd riddle (source):

From the American journal Scripta Mathematica:

An elementary school teacher in New York state had her purse stolen. The thief had to be Lilian, Judy, David, Theo, or Margaret. When questioned, each child made three statements:

Lilian:
(1) I didn’t take the purse.
(2) I have never in my life stolen anything.
(3) Theo did it.

Judy:
(4) I didn’t take the purse.
(5) My daddy is rich enough, and I have a purse of my own.
(6) Margaret knows who did it.

David:
(7) I didn’t take the purse.
(8) I didn’t know Margaret before I enrolled in this school.
(9) Theo did it.

Theo:
(10) I am not guilty.
(11) Margaret did it.
(12) Lillian is lying when she says I stole the purse.

Margaret:
(13) I didn’t take the teacher’s purse.
(14) Judy is guilty.
(15) David can vouch for me because he has known me since I was born.

Later, each child admitted that two of his statements were true and one was false. Assuming this is true, who stole the purse?

I spoiled the riddled for myself by accidentally looking at the answer =/

[Deku Trii]

Spoiler Below

Judy. It's easy once you figure out that any child who both specifically denied stealing it and accused someone else of stealing it cannot be guilty.

[CaptHayfever]

Spoiler Below

Since two of Theo's statements (10 & 12) are co-dependent, they must both be true & 11 must be false. Thus, Theo & Margaret are both innocent.

Since Theo is innocent, 9 is false, so David's other two statements (7 & 8) must be true.

Since 8 is true, 15 must be false, so Margaret's other two statements (13 & 14) must be true. Thus Judy is guilty.

And remember, "I'm-a Luigi, number one!"