A couple from Wisconsin has been charged with a scheme to murder two women using cyanide, with several investigators falling ill after exposure to the toxin, prosecutors and reports have stated.

Paul VanDuyne and Andrea Whitaker have been accused of concocting poisons as part of a detailed plan to kill two women, who were both former girlfriends of VanDuyne, as detailed by the Wisconsin Justice Department.

Prosecutors allege VanDuyne broke into a woman’s car in a Middleton Costco parking lot last month and contaminated her water bottle with cyanide.

According to Fox 47, the woman was informed by people outside her car that it had been tampered with, although she did not notice anything unusual at that moment.

She did find the water tasted funny, the outlet reported.

Two weeks later, the same thing is alleged to have happened again. This time, the woman brought the bottle to the police, who tested it and confirmed it contained cyanide. 

Around the same time, another woman in Rock County was hospitalized after drinking cyanide-tainted water found in her car after a gym visit. 

Both alleged victims briefly dated VanDuyne, prosecutors said. 

VanDuyne was arrested Sunday after the hazmat-linked investigations and after authorities caught him allegedly trying to help cover up evidence.

Police had been monitoring VanDuyne but were forced to move quickly when he tried to contact the Rock County woman last weekend. He was arrested and booked Sunday.

While in jail, VanDuyne called Whitaker and asked her to remove items from his house, prosecutors said.

Agents intercepted her leaving with her belongings. When searching her phone, they found multiple messages between the couple discussing different poisons.

Prosecutors believe the pair were planning to murder VanDuyne’s ex-girlfriends with poison.

At least seven state investigators on the case have been hospitalized for possible exposure to the poison, WISN.com reported. 

The outlet reported that Dane County Assistant District Attorney William Brown revealed Whitaker’s online history included searches for “Does potassium cyanide cloud water?” and “Sodium cyanide odor, sodium cyanide.”

Searches also included “What does cyanide look like?” and “Cyanide lethal,” he said. 

VanDuyne and Whitaker face charges in Rock County of attempted homicide, aggravated battery, reckless endangerment and stalking — all involving a dangerous weapon.

In Dane County, VanDuyne faces more charges for attempted homicide and stalking, while Whitaker is also accused of helping him and trying to cover it up.

Seven agencies were involved in the investigation, including the Wisconsin Department of Justice’s Division of Criminal Investigation, the Rock County Sheriff’s Office, the Wisconsin State Crime Laboratories and the FBI.