Crime Pet Duck Leads Police to Murder Victim and Elusive Clues: 'If I Could Give That Duck a Medal, I Would' Officials haven't determined when or how Nellie Sullivan, who was in her 90s, was killed By Chris Harris Chris Harris Twitter Chris Harris has been a senior true crime reporter for PEOPLE since late 2015. An award-winning journalist who has worked for Rolling Stone and MTV News, Chris enjoys prog rock, cycling, Marvel movies, IPAs, and roller coasters. People Editorial Guidelines Published on April 26, 2022 11:20 AM Share Tweet Pin Email Angela Wamsley and Mark Barnes. Photo: Buncombe County Sheriff's Office Someone's pet duck has helped investigators in western North Carolina close a missing person's investigation that began more than two years ago. On April 21, Angela Wamsley, 46, and Mark Barnes, 50, were formally charged with first-degree murder in connection with the death of Wamsley's grandmother, Nellie Sullivan. Officials have yet to determine when or how Sullivan was killed, but they believe she has been dead for "multiple" years. Wamsley and Barnes, a married couple, have been in custody since mid-December 2020, when the Buncombe County Sheriff's Office opened an investigation into Sullivan's disappearance, which was almost immediately deemed "suspicious," according to a statement from the sheriff's office. Early in the investigation, Wamsley and Barnes were charged with misdemeanor animal cruelty, unlawfully reconnecting a utility, animal abandonment and synthetic cannabinoid possession. Barnes was additionally charged with possession of a firearm by a convicted felon. Detectives had been searching for any sign of Sullivan — who was in her 90s, police said — since those initial arrests. Numerous search warrants were executed at various locations as part of the investigation, and authorities discovered that Wamsley and Barnes allegedly continued to collect the grandmother's benefits checks. The two also allegedly continued to have her prescriptions filled. "On December 20, 2021, Mr. Barnes was charged with concealing a death and Ms. Wamsley received the same charge on January 7, 2021," reads the sheriff's office's statement. "Wamsley was also charged with assault with a deadly weapon on a Detention Officer at the Buncombe County Detention Facility in January of 2021." Then, in March 2021, the pair were charged with obtaining a controlled substance by fraud or forgery, trafficking in heroin or opium by possession, trafficking in heroin or opium by transport and felony conspiracy. While Barnes provided authorities with a location, allegedly suggesting the missing woman's remains might be there, a search of the area turned up nothing. Without Sullivan's body, detectives were unable to accuse the couple of her murder. But that all changed on April 14, when a pet duck escaped its owners, and fatefully scurried beneath a trailer in Candler, N.C. Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases. In their efforts to reclaim the duck, the bird's owners came across the container Sullivan's body had been placed in. "If I could give that duck a medal, I would," Buncombe County Sheriff's Office Sgt. Mark Walker told WLOS News 13. An anthropologist is working to determine how long ago Sullivan, who suffered from health issues as well as dementia, was killed. It was unclear Tuesday if Barnes or Wamsley, who are being held without bond, had entered pleas to any of the charges against them. Their lawyers were unavailable for comment.