Chelsea Yellowbird, who was 23, was slain two months after her five-year-old nephew, Ethan Yellowbird, was killed by a gunshot as he slept in a bed in the house next to his aunt's on the Samson Cree reserve in Maskwacis, formerly known as Hobbema.
On Tuesday, Wacey Applegarth pleaded to second-degree murder while Randall Omeasoo pleaded guilty to manslaughter.
Both men had originally been charged with first-degree murder.
A third man, Shelby Minde, is scheduled to appear in court Nov. 13.
The case was cold for two years before a number of tips helped Maskawacis RCMP break the case open.
The reserve, about 90 kilometres south of Edmonton, has struggled with drug- and gang-related violence over the years.
Three teens pleaded guilty in 2012 to manslaughter in Ethan's death. They admitted to taking turns firing a gun at the home and accidentally killing the boy.
Madam Justice J.H. Goss will wait for a Gladue Report to be completed before sentencing. The report focuses on an aboriginal offender’s history and upbringing and will be presented to the court before sentencing occurs.