On Tuesday evening, New York police arrested four people with more than 350 bags of heroin among them, reportedly in connection with the fatal apparent overdose of actor Philip Seymour Hoffman over the weekend. The three men and one women all lived in one building in lower Manhattan that informants said was the origination point of Hoffman's heroin.

One witness told the Daily News that one of the 40 to 50 cops at the scene said, as two handcuffed suspects were led out of the building: "Philip Seymour Hoffman's drug dealer lived here."

"Police were not certain if those arrested actually sold the lethal heroin to Hoffman or if they are part of a larger drug distribution ring," the Daily News clarified, citing a police source. It's also possible they had nothing to do with supplying the actor. Regardless, the NYPD is making a concerted, public effort to track down the person or people who sold Hoffman his final hits.

But even if the cops do find the dealer, he or she (or they) will almost certainly never be convicted for Hoffman's overdose.

This "intense effort to determine the source of the drugs in an apparent accidental overdose is unusual," says CBS News. "Courts have found in past rulings that under state law drug dealers can't be held liable for a customer's death." The U.S. Supreme Court reached a similar conclusion on Jan. 27, a week before Hoffman's death.

In Burrage v. United States, the Supreme Court effectively whittled down a portion of the 1986 federal Controlled Substances Act that required a minimum 20-year sentence if a drug dealer distributed an illegal drug like heroin and "death or serious bodily injury results from the use of such substance." Federal prosecutors had been interpreting that statute as saying that if a drug contributed to a death, the dealer of said drug got an automatic 20 years. The Supreme Court said that prosecutors have to prove that the drug in question actually caused the person to die. "Is it sufficient that use of a drug made the victim's death 50 percent more likely? Fifteen percent? Five? Who knows?" Justice Scalia wrote. "Uncertainty of that kind cannot be squared with the beyond-a-reasonable-doubt standard applicable in criminal trials."

That's a much harder case to prove. The New York medical examiner is still determining the cause of death, but if the police reports are right — that Hoffman was found dead in the bathroom with a needle in his arm — heroin was almost certainly at least a contributing factor.

But police also reportedly found various prescription drugs, including buprenorphine (a drug used to treat heroin addiction), blood pressure mediation, and muscle relaxants. Hoffman had also reportedly taken up drinking again. And Juliet Papa at radio station 1010 WINS cites sources saying that cocaine and methamphetamines were also found in Hoffman's West Village apartment. If any of those substances are found in Hoffman's body, it will be nearly impossible to prove that heroin alone caused his death.

Now, Hoffman's dealer or dealers may well spend time behind bars for selling heroin to the actor and others, if police can find them and prosecutors can convince a jury of their guilt. But that's very different than being locked up for Hoffman's overdose. If jailed, they will be locked up for the crime they committed — selling illegal narcotics — not Hoffman's deadly lapse in judgment.