BRIAN ROSS INVESTIGATES BERNIE MADOFF: A MAN OF MANY SECRETS, ON "20/20," FRIDAY, JUNE 26 ON ABC

Plus: John Stossel Reports on President Obama's Healthcare Plan

And: A 16-Year-Old Girl the Size of an Infant Who Is Baffling the Medical World

Also: How a Teen Romance Turns Deadly When Jealously Enrages an Ex-Boyfriend

This coming Monday, Bernie Madoff will be sentenced for orchestrating Wall Street's biggest investment fraud ever -- swindling thousands of investors out of some 65 billion dollars over 20 years. He is a person of many secrets and appears to have very little remorse. But what's behind this man who was capable of pulling off such an unprecedented Ponzi scheme? Chief Investigative Correspondent Brian Ross reports new details of Madoff's personal life, including names in his "little black book," visits to massage parlors, plus an exclusive interview with his devoted secretary of 25 years. The report airs on 20/20," FRIDAY, JUNE 26 (10:00-11:00 p.m., ET) on the ABC Television Network.

Then: President Obama has been selling his plan for universal healthcare for everyone. But John Stossel says that what often sounds like a great idea has unintended consequences. Is insurance even a good thing? As Stossel questions: "Imagine what your life would be like if insurance paid for other things you buy. What if you had grocery insurance? You wouldn't care what things cost. Why use coupons? Why look for sales? I'll just buy-everything. My insurance company's paying." That increases costs, says Stossel: "When bills are paid with 'other people's money,' costs skyrocket." Many experts find apt comparisons between what may happen if government offers health insurance and Canada's single payer healthcare system. Canadian doctor David Gratzer, author of The Cure, thought the Canadian system was great until he started treating patients. "People line up for care, some of them die, that's what happens... You want to see your neurologist because of your stress headache? No problem! You just have to wait six months. You want an MRI? No problem! Free as the air! You just gotta wait six months," Dr. Gratzer tells Stossel.

And: At about 16 pounds and 30 inches, 16-year-old Brooke Greenberg is the size of an infant. She has not aged significantly, physically or apparently cognitively since she was a toddler. Will her baffling case shed light on the mysterious genetics behind aging? Is she the fountain of youth? Bob Brown reports.

Also: How did something that began as a teen romance between an outgoing girl and a shy boy turn into a one-sided obsession that ended in a heinous crime with two people killed? Deborah Roberts reports how a teen couple's loving relationship began to unravel with a spiral of jealous rage and harassing text messages and I-Ms.

"20/20" is anchored by Elizabeth Vargas and John Stossel. David Sloan is executive producer.