A constable with the Halifax Regional Police has been charged with theft related to an allegation he stole from an evidence locker a chemical used to dilute illegal drugs to increase their quantity.

Const. Laurence Gary Basso has also been charged with breach of trust and obstruction of justice, the province's Serious Incident Response Team said Wednesday.

The Serious Incident Response Team, an independent body that investigates serious incidents involving the police, says a substance known as "cut" went missing from the Halifax police exhibit locker. Cut generally refers to a chemical mixed with an illegal drug to increase the quantity.

"You take a cheaper substance, you mix it in with the more expensive substance and then you can sell the greater quantity for the more expensive price," said Ron MacDonald, the director of SIRT.

The cut was a powdered form of lidocaine, a topical medication used to numb tissue, MacDonald told the CBC's Elizabeth Chiu. He said 700 grams of lidocaine — worth about $2,500 — was allegedly removed from the locker.

'Significant' allegations

"Exhibits and their security are an essential feature of prosecutions and investigations of crime and any tampering with an exhibit can be seen as being a very significant … issue for the justice system in general, and in particular the police agency," said MacDonald.

"So any type of allegation of that nature is a significant one."

The charge of obstruction of justice was laid after Basso allegedly took steps to help a third party avoid detection and arrest by other members of the police force. MacDonald said the identity of the third party will not be released at this point.

SIRT director Ron MacDonald says these are the first ever charges of theft and breach of trust laid against a police officer by the watchdog. (Elizabeth Chiu/CBC)

The Serious Incident Response Team alleges both incidents happened between Jan. 1, 2015 and March 14, 2015.

Halifax Regional Police say the charges against Basso are "serious allegations" and are an isolated incident.

"Any time that charges are laid against a police officer, I think it's fair to say that that's a matter that is of significance. That's why SIRT is in existence," said MacDonald.

MacDonald said these are the first charges of theft and breach of trust laid against a police officer since the watchdog was established in 2012.

Basso will appear in court on March 30.