Criminal story

The task is easy, but interesting.

A teacher at one of New York's elementary schools lost her wallet. Only one of the five students could steal a wallet: Lilian, Judy, David, Theo or Margaret.
When interviewing these children, each of them gave three testimonies:

Lillian

1. I did not take the wallet;
2. I have never stolen anything in my life;
3. Theo did it.

Judy

1. I did not take the wallet;
2. My dad is rich enough and I have my own wallet;
3. Margaret knows who did it.

David

1. I did not take the wallet;
2. I was not familiar with Margaret until I entered school;
3. Theo did it.

Theo

1. That's not my fault;
2. This was done by Margaret;
3. Lilian is lying, claiming that I stole the wallet.

Margaret

1. I didn’t take the teacher’s wallet;
2. Judy is to blame;
3. David can vouch for me because he knows me from my birthday.

Upon further questioning, each of the students admitted that of the three statements made by him, two are true and one is false.
Determine which student has stolen his teacher’s wallet.