Ottawa police have seized an estimated $15 million worth of drug ingredients used to make a form of ecstasy, which only became illegal in Canada in March 2012, as a result of the investigation into a double-homicide at the Gloucester Centre shopping mall.

Graham Thomas, 35, was killed in a double fatal shooting at an east Ottawa mall last October. He was a father of twin one-year-olds. (Facebook)

Ottawa police's major crimes unit began their investigation in October 2011 after Graham Thomas, 35, and Jason Chapman, 31, were shot and killed at Caribbean Exposure, a tanning salon in the east Ottawa mall.

The force's drug unit executed a warrant within the last week at an east Ottawa location where they found the ingredients, Benzylpiperazine (BZP) and Trifluromethylphenylpiperazine (TFMPP), which are combined to make an illegal alternative to ecstasy.

Police said they seized a "significantly large amount" of the synthetic substance in both powder and pill form.

2 ingredients listed as 'controlled substances'

Health Canada's Food and Drug Regulations deemed the two ingredients "controlled substances" in March of this year.

"Effects associated with the use of products containing these substances include increased blood pressure, slowed breathing, hallucinations and seizures," the legislation reads.

"As there is evidence that increasing volumes of these substances are being imported into Canada and that products containing BZP and TFMPP are becoming more widely available."

No charges have been laid connected to the drug seizure.

The investigations into the drug seizure and double homicide continue, police said.