SAN DIEGO (CBS 8) - Most parents have never heard of the drug fentanyl, the synthetic pain medication that killed rock musician Prince.

In San Diego County, fentanyl deaths have now reached an all-time high. To make matters worse, sometimes people who overdose never knew they were taking fentanyl.

Looking back on the death of his son Jeremy, Leigh Hatfield never saw it coming.

“It was such a shock, such a surprise when it happened,” said Hatfield, a South Bay high school teacher who lives in Tierrasanta.

“He had a spontaneity that was pretty impressive. He felt like he had a good shot at doing standup comedy, which would have been pretty cool,” said Hatfield.

Jeremy Hatfield grew up in San Diego, attended the Army Navy Academy in Carlsbad, and died last year at the age of 22. He was found alone in his college dorm room at the University of New Mexico.

“The toxicology showed that he had 30 times the amount of fentanyl than the body can tolerate. So, he took an awful lot of it,” Hatfield said.

Fentanyl is one hundred times stronger than morphine and typically is not taken in pill form

Many people who overdose on fentanyl mistakenly believe they are taking an oxycontin pill; when, in fact, the pill is a black-market fake, laced with fentanyl instead.

“Lately, we've seen more counterfeit fentanyl enter the market,” said San Diego County Chief Deputy Medical Examiner Jonathan Lucas.

Lucas’ office sees one fentanyl death in San Diego County every 11 days.

“If you're just using an oxy pill every once in a while and you pick up an oxy pill that's been laced with fentanyl unknowingly -- you might have successfully kept that oxy habit from your family and friends because it doesn't really affect you in any real way – but if you get the wrong pill the fentanyl can just kill you,” said Lucas.

That's exactly what may have happened to Hatfield’s son, Jeremy.

“I think what we need to realize as a society is that they're going to do it, maybe more than we like,” said Hatfield, who recently spread his son's ashes atop Tahquitz Peak near Idyllwild.

His advice to other parents?

“Just have those conversations with them in every way possible, street smarts, school smarts, all that you can get access to,” said Hatfield.

Another tip for parents, if you have unused pain medication in your medicine cabinet, get rid of it.

You can drop off prescription drugs at any sheriff's station during normal business hours, no questions asked.