Ms Tolley, who was 30, was shot in her Ward Street flat in December 2016.
A 27-year-old was arrested yesterday and is due to appear in the Hutt Valley District Court today charged with murder.
Inspector Scott Miller said with a murder charge now laid, they would be going back to people already spoken to in the investigation.
He said the inquiry remained ongoing.
Inspector Miller said police were pleased that the arrest would help bring some closure to Lois's family and the Upper Hutt community.
On December 9, 2016, four people smashed their way into Ms Tolley's home. She was shot in what police described as an execution-style killing.
A year later police said the investigation team had worked through a list of more than 130 persons of interest as they attempted to build up a picture of what happened that night. At the time they had narrowed their list to about 12 people.
In December last year, investigation head Detective Senior Sergeant Glenn Barnett said Lois Tolley had become involved in the Upper Hutt drug scene and her death appeared to have been connected to that world and was possibly a targeted attack.
Ms Tolley's mother Cathrine said last year the family was tight-knit and her daughter's death had been devastating.
"They stole her future away from her and have devastated ours. It is so hard not hearing her voice and seeing her beautiful smile."
Detective Inspector Scott Miller said a lot of investigative work was being done in conjunction with Australian police.
