"There were very low concentrations of cannabis, but the signature was there," said Inspector Tommy van der Merwe, of the Forensic Science Laboratory.
The low concentrations could be attributed to the fact that cannabis begins to degrade after a short period of time, according to the scientist.
However, there is no doubt about the traces of cocaine. "The pipes we tested still had dirt in them which preserved the residues inside the stem and bowl," Van der Merwe said. Contamination was unlikely, he said. "The readings we got were the same as if it had tested a modern-day crack pipe."