Van Dam Hoang, 47, of Hawker, pleaded not guilty earlier this year to five counts of trafficking in heroin.

But in the ACT Magistrates Court on Tuesday, Hoang switched his plea to guilty as the charges were rolled up into a single count of trafficking in heroin between January 19 and March 2.

Police documents tendered to the court detail five drug deals in which Hoang sold a combined five ounces of heroin to an undercover officer in suburban Belconnen in exchange for $43,500.

The deals, which took place in Scullin and Hawker, were captured on video and audio surveillance devices.

Hoang dug the drug up from hiding spots in multiple locations, including next to the Southern Cross Early Childhood School in Scullin.

Laboratory testing of the heroin he sold to police indicated high purity levels, reaching 77.5 per cent in one instance.

When Hoang was arrested in March, police said in a statement that officers had seized about 150 grams of heroin with an estimated street value of $70,000 in a subsequent raid.

The statement said that following an increase in drug overdose deaths, detectives had "identified an organised criminal network involved in supplying heroin across north Canberra".

"The actions of officers in this case have prevented 1400 deals of heroin from hitting the streets, and reduced the impact on ACT emergency services in responding to drug overdose deaths," the statement said.

Prosecutors have previously told the ACT Magistrates Court that police consider Hoang to be "an upper-level supplier" of heroin in the territory.

On Tuesday, Magistrate James Lawton committed Hoang's case to the ACT Supreme Court for sentence.

The 47-year-old spent more than two weeks in custody following his arrest, but he is now on bail and is expected to appear in the higher court for the first time next Thursday.