Look for this to be a conversation topic in the morning. From the Associated Press:

Pittsburgh dentist Alfonso A. Costa pleaded guilty to a felony count of health care fraud after an FBI probe into his oral surgery practice found he had charged for procedures he never performed, according to court records.

Though the crime carries a potential sentence of up to 10 years in federal prison, Costa was sentenced to house arrest and probation after Carson helped petition a federal judge on behalf of the man he described as "one my closest, if not my very closest friend."

That's different from the position Carson later took as he prepared to launch his presidential campaign. In his 2013 political treatise, "America the Beautiful," Carson wrote that anyone found guilty of health care fraud should face the "Saudi Arabian Solution."

"Why don't people steal very often in Saudi Arabia?" asked Carson, a retired neurosurgeon. "Obviously because the punishment is the amputation of one or more fingers. I would not advocate chopping off people's limbs, but there would be some very stiff penalties for this kind of fraud, such as loss of one's medical license for life, no less than 10 years in prison and loss of all of one's personal possessions."

Despite that tough-on-crime message, records show Carson and his wife have maintained their business relationship with Costa in the years since the dentist's 2007 conviction. The breadth of the two men's business ties has not been previously reported, partly because details can be obscured in property and incorporation records.

Carson defended his relationship with Costa anew on Thursday, in a statement his campaign circulated among news organizations — but not the AP.

"Al Costa is my very best friend. I know his heart. I am proud to call him my friend. I have always and will continue to stand by him. That is what real friends do," Carson said.

Doug Watts, Carson's spokesman, said this week he was unable to respond to specific questions about land deals involving the candidate and Costa. He acknowledged they do have investments together.

Costa did not respond to messages seeking comment.

Before his criminal conviction and the revocation of his license to practice dentistry, Costa built a multimillion-dollar fortune through commercial real estate. Costa Land Co. and its affiliates own properties in at least five states and overseas.

Investments that Carson and his wife made through Costa earn the couple between $200,000 and $2 million a year, according to financial records Carson has filed.

Costa has also served on the board of Carson's charity, the Carson Scholars Fund, and leads its fundraising efforts in the Pittsburgh area to provide $1,000 college scholarships. Costa's son has worked with Carson's presidential campaign.

In 2007, a few months before Costa was charged, records show that two corporations were established in Pennsylvania called BenCan LLC and INBS LLC. Carson and his wife are listed as the sole members of the companies. Though the Carsons live outside Baltimore, the mailing address on the incorporation forms was Costa's home address in Pittsburgh.

BenCan and INBS then paid more than $3 million to purchase an office building in suburban Pittsburgh. The mailing address listed on the deed matches the office of Costa's firm, as does the address where property tax bills are sent.

That September, federal prosecutors accused Costa of fraud committed over a nearly five-year period. Investigators determined that Costa's dental practice charged more than 50 patients for procedures that had not been performed, resulting in a loss of more than $40,000 to insurance companies.

After Costa pleaded guilty, 40 of his family members, friends and patients wrote to the judge as character witnesses.

Carson was one of three people who also testified at Costa's 2008 sentencing hearing, stressing his friend's charitable work. He said they shared the "same values and principles" and their families vacationed together.

Prosecutors urged the judge to make an example of Costa, arguing that reducing his sentence would "create the appearance that a defendant's financial resources and prominent connections can skew the justice system in ways not available to persons of lesser means."

Costa got no prison time. He was sentenced to one year of house arrest and ordered to pay more than $294,000 in fines and restitution.

Though Costa was assigned to serve his sentence in his 8,300-square-foot mansion in nearby Fox Chapel, his lawyers repeatedly sought permission for him to travel. A few months after starting his sentence, Costa asked to travel to the White House for a ceremony where President George W. Bush presented Carson with the Presidential Medal of Freedom.

The judge denied that request, though Costa was later allowed to take a month-long trip to Italy while on probation to handle what his lawyer described as urgent business at a resort he owns.

While not mentioning Costa by name, in his book Carson recounts an anecdote of a successful oral surgeon and real estate developer who was persecuted by the government.

"My friend owns a spectacular home, a Manhattan penthouse, two Ferraris and a European villa," Carson wrote. "I believe the lead agent was either jealous of his success or incorrectly concluded that he had organized crime connections that produced his wealth."

In Carson's telling, there was no hard evidence but his friend pleaded guilty to avoid a trial and "put his family through so much trauma."

Costa continues to use his ties to Carson to promote his business. As of Thursday, the logo of the Carson Scholars Fund is featured prominently on the company's website, as is a personal testimonial from the presidential candidate.

Carson is listed among the celebrity guests who have stayed at Costa's villa on a cliff overlooking the Tyrrhenian Sea.

"This is the most beautiful spot on Earth," Carson is quoted as saying.