A Texas man was arrested by U.S. Marshals last week for not paying his $1,500 federal student loan -- for 29 years.

Paul Aker was arrested at his home and later brought before a judge to sign a payment plan for a loan he said he borrowed in 1987.

"I was unaware of any outstanding debt," Aker told CNNMoney on Tuesday. "I paid two other student loans and thought I had consolidated everything and paid it all off."

The U.S. Marshals Service made several attempts to serve Aker with a court order requesting that he appear in federal court and searched numerous known addresses, the agency said in a statement. The Marshals Service said it spoke with him by phone in 2012 requesting he appear in court, but he refused.

Aker told CNNMoney that he does not remember having that conversation, and said that he hasn't received any notification about the outstanding loan in a long time.

A judge issued a warrant for his arrest in December of 2012 after he failed to appear in court, the Marshals Service said.

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On Friday, Aker was approached by two Marshals outside of his home when he went to check his mail. Things quickly escalated when they attempted to arrest him.

"I went inside to get my gun because I didn't know who these guys were," he told CNNMoney.

The two Marshals requested backup after Aker said that he was armed. After about two hours, he put the gun down and went outside, where he was arrested without further incident, the Marshals Service said.

"I saw some local police officers outside and thought if they're here, this must be real," Aker said.

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The original loan was for $1,500, and with interest it now amounts to about $5,700. He said he agreed before a judge on Friday to start paying in installments of $200 a month immediately.

"I'm still shaken," Aker said. "Why send seven guys with guns about a student loan?"

It is not uncommon for U.S. Marshals to serve summonses to people who fail to appear in court regarding outstanding federal student loans. But a warrant is only issued after someone skips a court appearance.

Last year, such warrants were issued for 25 people in the Houston area, the Marshals Service said. Seven were arrested while the others came to court on their own to resolve the matter.

"Our goal is not to arrest people regarding this issue, but to give them a chance to comply with the court order and resolve their debt," a Marshals spokeswoman said.

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Former students get many chances to start repaying a federal loan before U.S. Marshals knock on the door.

Here's what typically happens after someone misses a payment:

After 90 days, a loan becomes delinquent, and possibly damages the borrower's credit score.

But it's not considered to be in default until 9 months go by without payment. By this point, the borrower should have heard from the lender several times. But if the borrower still doesn't pay, a collection agency steps in, which will also probably contact the former student.

The borrower's wages can be garnished and the government can withhold a tax refund.

The collection agency can then sue the borrower, though it doesn't have the authority to arrest them. But if the debt is still ignored and the person fails to appear in court, then a judge could issue a warrant for arrest. That's where the U.S. Marshals could come in.

At this point, a borrower will owe a lot more than the principal as interest, late fees, and collection fees add up.

At the end of 2014, there were 43.3 million Americans with student loans who owe a total of $1.3 trillion. About 11% are in default, which means they failed to pay for more than 9 months, according to the New York Federal Reserve. About 1,500 people in the Houston area have defaulted on federal student loans, according the the Marshals Service.

Correction: An earlier version of this story incorrectly stated that warrants for 1,500 people in the Houston area had been issued because they failed to appear in court for a hearing regarding unpaid student loans. The U.S. Marshals Service says that 1,500 people have been identified as defaulting on their federal loans, but have not been contacted yet.