Heroin overdose among experienced users with steady supplies are unheard of. Heroin is quite safe, actually. The overdose problem is usually among black-tar heroin users who inject or snort (rather than smoke or eat) who then buy white powder heroin. Black-tar heroin is very impure (20-30%), being manufactured directly from unpurified opium or poppy straw extract, while white powder heroin is very pure(80%+, unless heavily cut), being manufactured from purified morphine. Even when cut, white powder heroin tends to be at least twice a potent as black-tar. Furthermore, black-tar and white powder are misnomers; both are yellow to yellowish brown, which is how those overdoses happen.
Until recently, white powder heroin was only available in large cities such as NYC, but now it's moving West, leading to a string of overdose deaths along the east coast and as far west as Michigan.
If it were regulated and legal, this entire class of overdose deaths would be eliminated. Considering that this type of overdose death is the majority of overdose deaths in the US, we are killing people by keeping it illegal. Considering the rate of overdose deaths among long-time users, legalization would result in fewer overall deaths, even if everyone picked up the habit. Now that you know all this, you and all other prohibitionists, especially those in Congress, are engaged in willful murder.
Have fun sleeping tonight, murderer.