OSO — Snohomish County on Monday finished buying out properties in and around the site of the deadly 2014 Oso mudslide, acquiring the former home of a couple slain earlier this year.

The final property belonged to the estate of Patrick Shunn and Monique Patenaude, who were shot dead in April. A former neighbor is charged with aggravated murder in their deaths. The suspect’s brother has pleaded guilty to helping cover up the double homicide.

The county paid about $340,000 for the 21-acre property on Whitman Road, said Heather Kelly, who has headed up the county’s long-term slide-recovery efforts. The county purchased 74 of 100 properties eligible for buyouts under a Federal Emergency Management Agency grant program. Owners of the other properties declined to participate.

The county has spent $4.1 million on the buyouts, Kelly said. All buyout properties must remain as undeveloped open space.

Separately, efforts are under way to plan a permanent memorial to the 43 people killed in the slide.