INDIANAPOLIS, Ind. -

Their crime didn't take a lot of know-how, but in the end a group of Nigerian con-artists stole hundreds of thousands of dollars from major U.S. companies. The bank fraud case was finally cracked by U.S. postal inspectors.

Surveillance photos captured the image of Olasunka Abaje in a bank depositing stolen checks.

"We have people here who were depositing stolen checks from businesses all over the country," said Inspector DeMarkus Calhoun.

Calhoun often works undercover. His bank fraud investigation led him straight to Abaje.

"The main player here is a Nigerian National; he's here on an expired Student Visa," Calhoun explained.

First, he would steal checks from big companies, wash them and alter the recipient to one of his false company names, then deposit them in the bank. He or other co-conspirators would withdraw the money quickly before companies noticed a problem.

"The majority of the funds they stole went back to Nigeria to fund the overall larger organization. He was the money-man really," said Calhoun.

A search warrant of Abaje's home uncovered more evidence including as many as 15 fraudulent credit cards.

"During the search warrant we found computers, ledgers, different account names, different identifiers for himself, we found photos of him that he was using to put into different passports," Calhoun explained.

In all, businesses targeted by this crime ring lost more than $450,000.

"To come here and set up an enterprise where you're stealing from the government, stealing from banking officials and stealing from individual customers, the reputation of the Nigerian National undermines what the people who come here to work are trying to do," said Calhoun.

Postal inspectors say there is a way to protect yourself from a crime like this.

"Know your money," warned Calhoun. "Check your accounts regularly. Go through your statement."

Abaje confessed to his crimes and faces 25 to 30 years in prison for bank fraud.