Re " increase in deaths due to heroin laced with fentanyl ":
That's a possible explanation. Another is that the heroin he injected is was purer - stronger - than the usual stuff doing the rounds and he should have used a smaller dose. But stronger/purer heroin is more desirable than heroin cut with filler - as long as you're aware of what you're injecting. I knew a Scottish smack addict who confided to me one time that whenever he heard of a junkie dying of an overdose his first thought was never sympathy but was always: "I wonder who the dead addict bought that batch from?" and "Can I get my hands on some for myself" .