A couple were arrested Monday on suspicion of killing five elderly residents at a retirement home in southwest England, police said.

Police first questioned nurse Rachel Baker, 45, and her husband Leigh, 48, a chef, after 97-year-old Lucy Cox died on New Year's Day at a nursing home in Butleigh, 130 miles (210 kilometers) southwest of London, Yeovil police spokesman Dan Mountain said.

As part of the investigation, detectives exhumed the remains of three other former residents to carry out toxicology tests and establish whether they had been poisoned, Mountain said.

The Bakers were arrested on suspicion of the murder of four women and one man, theft and unlawful possession of controlled prescribed drugs and attempting to pervert the course of justice, Mountain said.

The couple were arrested in January but released on bail and they were re-arrested Monday during separate appointments with police, he added. The couple have been detained in custody, the spokesman said.

The Commission for Social Care Inspectorate, which is responsible for nursing homes, obtained a court order to close the retirement home in March.

The home was owned by Leigh Baker's parents, June and Malcolm, but Rachel Baker had managed it since 1988.