June 3, 2011  -- Despite being linked to multiple deaths, powerful synthetic drugs -- from cocaine-like "bath salts" to what kids call "legal marijuana" -- are sold to teenagers legally in stores and online with little oversight, an ABC News investigation found. The investigation airs tonight on "World News with Diane Sawyer" and "20/20."

The so-called legal highs first appeared on the European club scene in the mid-2000s and can be used to mimic the effects of illegal drugs. But according to experts, the side effects of the substitute chemicals are unpredictable and can be disastrous for those that take them.

"They're selling time bombs," Louisiana Poison Control Center Director Dr. Mark Ryan told ABC News of bath salts, which have nothing to do with the products long used in bathing. "We've had some people show up who are complaining of chest pains so severe that they think they're having a heart attack. They think they're dying... They have extreme paranoia. They're having hallucinations. They see things, they hear things, monsters, demons, aliens."

It's a scene that the horrified parents of one Louisiana teen witnessed firsthand just hours before their 21-year-old son took his own life in November.

After purchasing a packet of bath salts called Cloud Nine, BMX rider Dickie Sanders snorted the powder inside the packet and soon experienced waves of hallucinations lasting days, his father, Rick Sanders, said. Dickie was convinced there were dozens of police cars and helicopters just outside the home, even though there were none. Then, suddenly, he grabbed a knife and sliced at his throat from ear to ear.

He survived the knife wound and told his mother he had had enough.

"He actually looked at me and said, 'I can't handle what this drug has done to me. I'm never going to touch anything again,'" Julie Sanders said.

But hours later and without warning, Dickie had another psychotic episode and shot himself with a rifle.

"His eyes were fixed and dilated," his father Rick said. "I reached down, felt some pulses... his hands were just totally bloodied. And I said, 'Baby, he's dead. We've lost him. He's gone.'

"He took his life because he was just scared out of his mind. This drug destroyed him," he said.

BMX star Terry Adams, who rode often with Dickie, said Dickie had been one of the happiest people he'd ever known.

"I loved Dickie like a brother," he said. "I can't see how such a happy kid could take his own life. I will never understand it."

In addition to Dickie's death, bath salts drugs have been connected to a string of bizarre, violent episodes this year alone, including the death of a 23-year-old Florida man in early April, a murder-suicide in Washington state just days later and the slaying of a goat in West Virginia in May.

Another Suicide Linked to 'Legal Pot'

Another group of legal products that are widely available can be used to mimic the effects of marijuana. With names like Spice and K2, the synthetic drugs are popular enough to warrant dozens of YouTube videos devoted to them.

But Dr. M. David Lewis, Medical Director at the Visions Treatment Center in Malibu, Calif., said those drugs can be especially dangerous for teens.

"K2 and Spice are tremendous psychoactive drugs," Lewis said. "And if you take a developing brain... what you really have is a chemistry experiment."

Drug treatment centers across the country reported they are being flooded with teens who have become addicted to drugs like K2 and Spice. Since 2010 alone there have been 4,000 calls into poison control relating to the drugs.

After 18-year-old David Rozga of Indianola, Iowa, suddenly took his own life with a rifle last year soon after graduating high school, his parents were convinced the synthetic drugs played a major part.

"He just continued to become agitated -- indicating that he felt like he was in hell," David's father Mike Rozga said. His girlfriend at the time said it was clear David was under the influence of something.

"David did not do this intentionally," girlfriend Carrie Jackson told ABC News. "He was like in an altered state and, you know, he would never do this or hurt us or hurt anyone else or hurt himself."

Mike Rozga said before his death his son went to a local mall and legally purchased K2.

READ: Amazon.com Sells Legal Pot

Retailers say they have their own standards and most won't sell to anyone under 18. But ABC News hidden cameras caught two retailers -- one in New York City and one in Los Angeles -- selling Spice to a 14- and 16-year-old, respectively, without ever asking for ID.

WATCH Hidden Camera: Stores Sell 'Legal Pot' to Kids

Retail store trade groups say that as long as the products are legal -- and there is no federal regulation banning the chemicals -- there is no reason not to sell it. Dan Francis of the Retail Compliance Association said the products are nowhere near as dangerous as some foods that trigger allergies.

"It's not a dangerous product, much less dangerous than, say, peanuts," Francis said. "A ban is dangerous... because it sends it underground. And I'd like to ask the government what is wrong with euphoria and who gave them the right to regulate it?"

However, Detective Sergeant Brian Sher, who investigated David Rozga's death, places the blame for the boy's death directly on K2.

"I want people to know that," said Sher. "There are nay-sayers, but I can say definitively there's just nothing in the investigation to show that. Given what we know about K2 and Spice, David's anxiety, his feeling like he was in hell, has happened in many other cases."

Click Here for the Blotter Homepage.