Authorities are still investigating the official cause of Phillip Seymour Hoffman's death, but we know the actor struggled with addiction and investigators have confirmed the presence of heroin in his apartment.

It's a growing problem in this country, and heroin use here has doubled since 2007. According to the DEA, heroin seizures in New York State are up nearly 70 percent over the last four years.

For more on why use of the drug is on the rise, we turn now to LA Times reporter Sam Quinones, who's currently working on a book about the recent heroin surge.