Two Florida sisters were arrested Tuesday after a man with whom both of them were romantically involved told police that the pair was guilty of murdering their father, who died four years ago.

Mary-Beth Tomaselli, 63, and Linda Roberts, 61, each faced a charge of first-degree murder for ending the life of their father, Anthony Tomaselli, who was 85 years old at the time of his death in 2015. They admitted to killing their father after failing to euthanize him, Tampa Bay Times reported

Anthony’s death was originally ruled as natural, due to his age and health problems. On March 6, 2015, paramedics rushed to the man’s house in Palm Harbor, Pinellas County, which was also inhabited by the accused sisters and their mother. They found the victim unconscious upon arrival. After they failed to revive him, he was declared dead. 

When the two sisters were interviewed by authorities back then, their version of the event matched – they found their father sleeping on the couch and when went to check on him, discovered that he was not breathing. They then performed CPR on him and dialed 911. The authorities found no reason to doubt the pair and decided not to perform an autopsy on the body. The family’s longtime doctor signed the death certificate which confirmed that Anthony had died of natural causes.

“Every single day we respond to natural death calls and if there is no evidence of foul play, no suspected criminal activity, no reason to believe anything other than a natural death, none of that is checked. When you have a guy who is 85-years-old and he has cancer, he has dementia and he obviously has heart problems, he has a pacemaker…” Pinellas Sheriff Bob Gualtieri said Tuesday, explaining why Mary-Beth and Roberts were able to walk scot-free for years.

In reality, the sisters faked the entire account of events they had initially provided to the authorities. The plan to euthanize their father was hatched after both of them found out that Anthony’s days were numbered and he didn’t want to be put in an assisted living facility.

On March 5, 2015, the women spiked their father’s alcoholic drink with “excessive” sleeping pills, hoping it would kill him. Instead, the alcohol content in the beverage ended up dissolving the pills, negating its deadly effect. When the pair found the victim still alive on the couch, with labored breathing, they tried to use a pillow to suffocate him. When they were still unable to kill him, the daughters forced a rag down his throat and pinched his nose. Eventually, Anthony died.

“It was the ‘perfect’ murder,” Gualtieri said.

On Feb. 19, a man, whose name was withheld for privacy reasons, contacted the police, saying he was dating both Mary-Beth and Roberts and one of them confessed to killing the victim with the help of her sister.

The man said he first met Mary-Beth at a bar in August and became romantically involved with her. A while later, she introduced him to Roberts, who also started getting intimate with him. Soon after, Roberts started behaving oddly. “It was clear something was troubling her,” the sheriff said.

Roberts invited the man to her house on Feb. 12 and confessed to “euthanizing” her father. The man immediately took out his phone and recorded the confession. It was unclear if the police were in possession of the evidence that proved the women’s guilt.

When the sisters were questioned by investigators, both of them confessed to the murder, although they kept on using words like “euthanized” in their confession. "They clearly knew what they were doing,” the sheriff said.

Mary-Beth and Roberts were booked into the Pinellas County jail.

Handcuffs Mary-Beth Tomaselli, 63, and Linda Roberts, 61, each faced a charge of first-degree murder. In this photo, a border patrol agent handcuffs a woman during a training scenario at the Border Patrol Academy in Artesia, New Mexico, Aug. 2, 2017. Photo: John Moore/Getty Images