For five years, Mathy Downing has struggled for an explanation.
Why would her daughter Candace - a happy 12-year-old - hang herself from the bedpost, leaving no notes and no clue?
"We had no warning," Downing said. "Absolutely no warning."
The Downings blame Candace's suicide on the antidepressant drug Zoloft.
They wondered why the doctor gave such a powerful drug when Candace's only complaint was anxiety in school. Then recently, in their lawsuit against the doctor, they think they found an answer, CBS News correspondent Wyatt Andrews reports.
"I said, 'wait a second … what?'" said Candace's father, Andy Downing.
Wait a second, because Candace's doctor, Matheme Selassie, had been paid around $12,000 making speeches touting Zoloft, with some of the payments coming from Pfizer, the drug's manufacturer.
The Downings believe the money influenced the prescription.
"Did the doctor tell you he was taking Pfizer money?" Andrews asked Mathy Downing.
"Absolutely not," she said. "How dare he! How dare he take money for a medication that killed our daughter."
Today the chances are good your doctor accepts benefits from drug companies - and not just the free samples and the pens you see in most doctors' offices.
Estimates say drug-company payments to doctors go as high as $57 billion a year, according to a University of Quebec study, covering consulting fees, speaking fees on drugs, and medical seminars on the benefits of drugs.
That means the industry spends far more money marketing to doctors than it spends on advertising.
"If they are being paid, it ought to be reported," said Sen. Charles Grassley, R-Iowa.
Grassley is also looking at the money drug companies pay doctors for academic research. He is investigating some 20 top medical schools - including Harvard, Stanford and the University of Cincinnati, for under-reporting the income top researchers are getting from the drug industry.
Grassley wants to learn if the money is influencing research.
What kind of flag does that raise for Grassley?
"Well, it raises a flag to me that they might have something to hide," he said. "It raises a flag that the university doesn't care."
Biederman tells CBS News some of that industry money was "not personal income," and that his life's work is devoted solely "to rigorous and objective study."
Fixing this problem is complicated because some relationships between doctors and drug companies are legitimate, and necessary to achieve breakthrough therapies. Sen. Grassley says the answer is more public information.
Grassley and other senators have proposed a law requiring drug companies to report any payments to doctors of more than $500. That reporting will be available publically on a government Web site.
"There has to be full transparency," Mathy Downing said. "Parents, families have the right to all the information."
As for the suicide of Candace Downing, Selassie says in a deposition he was paid to speak about adult use of Zoloft. He declined further comment.
Pfizer, in a statement says its paid consulting work with doctors helps the company learn "how to reduce adverse reactions ... and improve effectiveness."
But the big question for the Downings is still about the money.
How much of the industry's money is buying legitimate consultations, and how much of it could be buying the wrong prescription?