"I found it is all mosaic floor," Yehuda Batir says in his broken Hebrew. He is 25, born in Uzbekistan, has been in Israel only two and a half years and is already serving time in Megiddo Prison for domestic violence. Now he is working there as part of a "rescue dig" organized by the Israel Antiquities Authority (IAA), which is uncovering what turned out to be a mosaic of perhaps the oldest church ever found anywhere, dating back to the fourth century C.E.

"First I found corner," Batir continues. "I go, dig with hoe, saw here a little, 10 centimeters, and I think to myself there is something here. There was plaster, shards, no pictures. After that I saw fish and I know it is Christian."

The excavations began nine months ago. In February 2005, Megiddo Prison was transferred from the auspices of the Israel Defense Forces to the Israel Prisons Service (IPS), which decided to build permanent structures on the premises to replace the tents there. Of the four areas in which excavation has taken place, the IAA has already released three for continued construction. The fourth area turned up a treasure.

"I am very happy that I found," Batir boasts. "I told my friends, they did not believe what is here. After, they saw on television."

For working at the dig, from 4:45 A.M. until 1:30 P.M., each prisoner gets NIS 30 a day. "Before this I sewed shoes, more money," says Raphael Yohai, 38, divorced and the father of two daughters, aged 18 and 19, who is doing five years for an armed robbery, during which someone was shot and afterward "turned dead in the hospital," as he puts it. He came to Israel 18 years ago from the Caucasus and will be freed in another three months. He is serving his time in Hermon Prison, from which he comes to Megiddo every morning at 6. After his release he is going to Amsterdam. He has lunch with his buddies in the staff mess hall, a meat meal with side dishes. After work he takes a shower and works out.

The dig is being supervised by Yotam Tepper. Clad in a hat that protects the back of his neck as well as his face from the sun, and dark sunglasses of an unusual design, Tepper, 38, describes the educational nature of his job.

"We are teaching work to people who have never worked or who worked at illegal things. Some of them are enthusiastic and are learning excavation management, becoming professionals. I am not interested in who did what I don't want to hear about or get entangled personally with them. I would definitely prefer to work with people who are trained in archaeology, but I accept the circumstances. They are the ones doing the work, and there is an attitude of respect and fairness toward them."

Between 30 and 40 prisoners are working in a huge army tent that covers the site and the mosaic floor. Tepper also talks to them about history and archaeology. Do they take an interest in things? "Absolutely," he replies. "They ask me where I am from in Israel, what kind of car I have, what I studied."

The IPS official in charge of the group is Ossam Kiezel, 41, from the village of Maghar, the commander of a wing in the prison, whose rank is the equivalent of a police chief inspector. He has been with the service for 20 years and is married and the father of five. He too is enjoying the joint initiative with the IAA.

Kiezel: "It is very nice because, first of all, it is a new sphere in the service. You learn a lot and enrich your knowledge. We learned about different periods, how pottery is made. A prisoner who gets used to working - that is part of his rehabilitation, a road to good citizenship. To sit in the barracks is degenerating; you get used to not working. At first the prisoners didn't want to work at this, but now they are asking me to stay in the excavations."

Yohai confirms this. "Before I did not want, when I found church I wanted," he says. Since joining, he has been "looking for all kinds of old things, coins, ceramics, cups." Would he dare - excuse the question - take a souvenir home? "If Israel gives souvenir, good, but not to steal, no way. This is history of State of Israel. Better to take bank and not things like this. You get a blow from God. This belongs State of Israel," he says emotionally, then adding, "What take? It is nonsense, it is dead. What I do with it?"