This article contains plot spoilers for the 2017 series of Twin Peaks.
Detective Dave Macklay was a detective with the Buckhorn Police Department.
Macklay arrived at the apartment of Ruth Davenport, who had been found dead. Constance Talbot investigated the scene and they pulled off the bedsheet supposedly covering Ruth's body to find that her head had been severed and a man's headless body was placed on the bed.
Talbot informed Dave that the head was confirmed as Ruth Davenport's and that fingerprints were found at the scene, matching those of William Hastings, Macklay's fishing buddy and friend since high school. He went to Hastings' home and arrested him.
Dave questioned Bill, whose story lined up until there was a 45 to 50-minute gap between his leaving a meeting on the night of the murder and his arrival at home. Macklay found this strange and Hastings eventually blamed it on taking his assistant a ride home. The detective then escorted Bill to a jail cell.
With a search warrant, Macklay, Harrison, and other officers went to the Hastings home. In Bill's car, they found a piece of flesh.
Macklay allowed Phyllis to briefly speak with her husband, which became a bitter conversation between the couple.
Lieutenant Cynthia Knox of the United States Air Force later came to observe the John Doe. Soon after, the body was identifed as Major Garland Briggs and was examined by the FBI's Deputy Director Gordon Cole and Agents Albert Rosenfield and Tammy Preston, whom Macklay told the circumstances of the body's discovery and that Hastings had an interest in alternate dimensions prior to the murder of Ruth Davenport.
Hastings led Macklay and the FBI to where he claimed to have entered "the zone," an alternate dimension. As the FBI investigated, Macklay remained in his car until Hasting's head suddenly exploded and he called for backup.