Even though Cassie's the third girl under the age of 16 to die in a month after taking "E," Graham Jones, chief toxicologist with the Edmonton medical examiner's office, says it's "relatively uncommon" for people to die of an overdose of ecstasy compared to other drugs.

But police warn the pills, which are imported into Edmonton from clandestine labs in Europe, Asia and the west coast, are a "cornucopia of chemicals" that varies from batch to batch.

They've seized shipments of ecstasy ( a chemical known as MDMA ) that is mixed with such additives as crystal meth, animal tranquilizer, dextromathorphine, Viagra and even high concentrations of caffeine.

And those are just the active ingredients. Any number of other chemicals are dumped into them as fillers.

"Every tablet that you take, you're dealing with an unknown," said Det. Guy Pilon of the Edmonton police drug squad. "It's a whole random mixture and you're literally at the mercy of the cook."

Even the concentration of E in each pill varies dangerously, Jones said. The ME's office has found they can range anywhere from 50 to 1,000 milligrams per tablet.

It's estimated that around 100 mg is enough for an average-sized person to get high, and anything over 200 mg is potentially dangerous.

Cassie, 14, and friend Ashley were at a Rock 'n' Ride Dance Party at West Edmonton Mall on April 24. They took some ecstasy but got so sick they had to be taken to hospital.

Her friend recovered, but Cassie died over the weekend.

Cassie's mom, Angela Eyre, said her daughter's friends told her she took six hits of E, and that the pills were what's known as a triple stack, or three times the regular dosage.

"( Whoever ) sold it to her ... he did not tell her what he was giving her. He knew what he had," she said yesterday.

In late March, two girls on the Paul Band First Nation west of Edmonton died after taking ecstasy at a party. Several others were also hospitalized.

Pilon said ecstasy is plentiful in Edmonton, "and it's a drug that is more aligned with young people."

Ecstasy affects users' moods. It fills them with euphoria, increases energy levels, intensifies their senses and gives them a feeling of increased mental clarity.

It also dramatically raises their body temperature, dehydrates them, sends their heart racing, increases blood pressure and radically changes their body's electrolyte concentrations.

One city cop, who's supervised large, public teen parties, says they're a "perfect storm" of conditions that can lead to kids overdosing.

"You've got these kids, some of whom are headed for gangs but aren't there yet," explained the cop, who spoke on condition of anonymity. "You've got these young, innocent girls, who want to fit in and are dressing too provocatively for their age, you've got big crowds, noise, flashing lights.

"Conditions are perfect for someone who wants to exploit the dynamics."

Eyre said she doesn't hold Rock 'n' Ride responsible for what happened, but said drug dealers will find ways to take advantage of young teens.

"My daughter gave me a purpose," Eyre said. "To get this drug off the street, to get kids to see how dangerous it is."

While she's in frequent contact with Ashley, Eyre said she hasn't spoken to her specifically about what happened on that tragic night. For now, she wants to give herself and Ashley time to grieve.

"This is the hardest time for her," she said.