Sen. Paula Simons is being sued for defamation in a $500,000 lawsuit filed Monday in the Court of Queen's Bench in Wetaskiwin, Alta.

The suit was launched by the man and woman who were the caregivers to a four-year-old girl named Serenity, who died in September 2014.

Her cause of death was determined to be blunt-force head trauma and its complications. Her former caregivers have said she fell from a tire swing.

CBC News is not naming the former guardians in order to protect the identities of Serenity's brother and sister.

More than three years after Serenity died, the couple was charged with a single count of failing to provide the necessaries of life. A lengthy preliminary hearing was held. In August, the charge against the couple was stayed.

The civil suit against Simons takes issue with comments she made on social media the day the charge was stayed.

Sen. Paula Simons faces a $500,000 defamation lawsuit. (Supplied by Paula Simons)

She wrote, "I was not in the courtroom for the preliminary inquiry, so I did not hear the evidence. And even if I had, I couldn't discuss it, because it's subject to a publication ban. So I have no informed public comment to make on the Crown's decision to stay the charges. Rather than speculate, I'll let this column speak for itself."

Simons, who was a well-known journalist before being appointed to the Senate in 2018, reposted a column she'd written for the Edmonton Journal in November 2016.

The column makes reference to possible sexual injuries and starvation.

In their statement of claim, the couple seek $500,000 in general damages and other "aggravated and punitive damages" as may be proven at trial. They also seek an injunction restraining Simons from further publishing the words they say are defamatory.

"We are alleging that Ms. Simons has essentially defamed my clients by posting incorrect information which would suggest that my clients were involved in sexual assault against the child Serenity — that the child died from a non-accidental death, a death that was essentially criminal in nature," lawyer Joshua Asp told CBC News.

The lawsuit says, in part: "In their natural and ordinary meaning, the said words meant and were understood to mean the plaintiffs were involved in the physical and sexual abuse of the child, that the child did not die as a result of an accidental fall from a swing, that the child's death was a homicide or criminal in nature and that the plaintiffs should not have children in their care."

Wetaskiwin lawyer Joshua Asp filed a civil suit against Sen. Paula Simons on Monday in Court of Queen's Bench on behalf of his clients. (Dave Bajer/CBC )

Asp said he was surprised Simons would repost her story given her appointment to the Senate.

"It does appear that she is publishing this in her capacity as a senator. So that is surprising," Asp said. "She did publish it on a Facebook page as well as a Twitter page that identifies her as a senator."

As of Monday, there was no posting about Serenity on the senator's Facebook page. Her Twitter comments were still online.

Simons said Monday she had not heard about the lawsuit.

"That is news to me," she said. "I have not been served as yet. Right now, I have no comment."

Asp said he believes his clients deserve compensation.

"This is about sending a message to people that if they're going to publish or convey information that suggests innocent people are responsible for sexually assaulting a child, or murdering a child or abusing a child, that they should ensure that information is correct and that they have a duty to get their facts straight," Asp said.

Allegations contained in the statement of claim have not been proven in court.