CHICAGO (CBS) — Two brothers make a tragic mistake. Smoking synthetic marijuana laced with rat poison.

One died. Now his brother is telling his excruciating story of survival.

2 Investigator Dave Savini spoke to the son and his mother.

“I miss his smile. He had a little smirk,” said Brandon’s mom Angela Darsham. “We ask where did we go wrong.”

Darsham wants you to see what happened to her 22-year-old son Brandon as a warning.

Hospitalized and fighting for his life, Brandon died days later. Killed after smoking synthetic marijuana someone laced with rat poison.

“They said he had a massive stroke and was never going to come back,” said Darsham.

Her other son Nathan was also poisoned and hospitalized at the same time.

“It’s hard not just losing one, but seeing both of them at the hospital at the same time,” she said.

The blood-thinning rat poisoning is put in synthetics known by many names including K2, Spice, Pep.  It has become a statewide public health crisis.

“I was pretty sick. I was throwing up the blood and everything,” said Nathan.

Brandon was also vomiting and bleeding.

At the hospital that same night Angela Darsham met other families affected by the rat poison-laced drugs.

“They wheeled them in, one after another after another and I had to sit on the ICU floor and just watch more people more kids coming through the emergency rooms,” said Darsham.

“It will take everything from you. Literally everything,” Nathan said.

Multiple police agencies continue investigating. In Pekin, police recently arrested Lonnie Smith for drug-induced homicide after selling a batch that killed a man.

When asked if Brandon bought stuff from him, Nathan said yes.

The brothers have smoked over the years. But the most recent bag both brothers shared came from another dealer.

How Brandon died and Nathan survived is unclear.

Authorities said it could be Brandon smoked a portion of the leaves that had more of the poison sprayed on it.

Nathan is still in danger of suffering a sudden stroke and under a doctor’s care takes vitamin K. 30 pills a day.

He’s so addicted he already broke the promise he made to his dying brother to get clean.

Now his mother fears her final words whispered to one son may soon be said to the other.

“I loved him. And I was sorry I couldn’t change anything,” said Darsham as she wiped away tears.

In death, Brandon helped others by being an organ donor.

There have been no arrests in the case.

There have been 155 overdoses and four deaths tied to this outbreak. The most common ages of an overdose victim is between 25 and 44.