(CNN) A Kentucky lawmaker accused of sexually assaulting a teenage girl in 2013 killed himself Wednesday, officials say, a day after he denied the allegations.

Republican state Rep. Dan Johnson, 57, was found dead of a single gunshot wound near Mount Washington, Bullitt County Coroner Dave Billings said.

Johnson drove onto a bridge in a rural area southeast of Louisville, parked and shot himself in front of his car, Sheriff Donnie Tinnell told CNN affiliate WDRB

Billings ruled Johnson's death a suicide on Thursday after an autopsy, Deputy Coroner Clayton Brunson said.

Shortly before his death, Johnson posted a rambling message on social media, denying the sexual assault allegations and urging his family to stay strong for his wife.

Relatives became concerned after seeing the post and reached out to law enforcement, who pinged Johnson's phone and later discovered his body, according to Billings.

Billings said he was called to the scene around 7:30 p.m. Authorities discovered Johnson's body in front of his truck and a 40-caliber semi-automatic handgun nearby, he said.

CNN has reached out to the Bullitt County Sheriff's Office and the Kentucky governor's office but has not heard back.

Investigation reopened

Just 24 hours before his death, Johnson denied sexual assault allegations detailed in a lengthy investigation by the Kentucky Center for Investigative Reporting.

His accuser said the alleged sexual assault took place in the early hours of New Year's Day in 2013 when she was 17, according to the center's explosive investigative report published Monday. The accuser, identified as Maranda Richmond, is now 21.

CNN's policy is not to name victims of sexual assault or rape unless they make their names public.

Richmond said she was staying in a living area of Louisville's Heart of Fire Church, where Johnson was pastor, when he drunkenly kissed and fondled her underneath her clothes, according to the investigative report.

She reported the incident to authorities in April 2013, and the Louisville Metro Police Department opened an investigation but closed it without charging Johnson, according to the Kentucky Center for Investigative Reporting.

The center got its hands on police documents about the accusations and interviewed Richmond, leading to its story on how Johnson allegedly forced himself on her when she was a teenager.

Johnson denied the allegations, a day after the center published its report, saying Richmond was motivated by his political opponents.

"This allegation concerning this young girl absolutely has no merit," he said. "As a matter of fact, some of this I heard yesterday for the first time as I read the story."

The same day Johnson held a news conference, the Kentucky Center for Investigative Reporting confirmed that Louisville detectives reopened the investigation.

Social media post

Johnson posted a message on his Facebook page Wednesday evening, saying the accusations "are false" and "only God knows the truth." The post appears to have been deleted.

"GOD and only GOD knows the truth, nothing is the way they make it out to be. AMERICA will not survive this type of judge and jury fake news. Conservatives take a stand," his post read.

"I LOVE GOD and I LOVE MY WIFE, who is the best WIFE in the world ... 9-11-2001 NYC/WTC, PTSD 24/7 16 years is a sickness that will take my life, I cannot handle it any longer."

Johnson had claimed he helped give the last rites to victims of the September 11, 2001, attacks, according to the Kentucky Center for Investigative Reporting.

Officials mourn Johnson

The report of the alleged sexual assault was not the first time Johnson made national headlines.

He won the 49th District State House race in Kentucky last year despite his Facebook posts that compared then-President Barack Obama and first lady Michelle Obama to monkeys. At the time, he shunned calls for him to drop out of the race -- and ultimately won the election.

Saddened to hear of tonight's death of KY Representative Dan Johnson...My heart breaks for his family tonight...These are heavy days in Frankfort and in America...May God indeed shed His grace on us all...We sure need it... — Governor Matt Bevin (@GovMattBevin) December 14, 2017

Fellow lawmakers mourned his death Wednesday night.

"Saddened to hear of tonight's death of KY Representative Dan Johnson," Gov. Matt Bevin tweeted Wednesday night.

Republican Sen. Rand Paul tweeted he's praying for Johnson's loved ones.

Just terrible news from Kentucky tonight on the passing of Rep. Dan Johnson. I cannot imagine his pain or the heartbreak his family is dealing with tonight. Kelley and I pray for his loved ones. — Senator Rand Paul (@RandPaul) December 14, 2017

"Just terrible news from Kentucky tonight on the passing of Rep. Dan Johnson," he said Wednesday. "I cannot imagine his pain or the heartbreak his family is dealing with tonight."

Michael Skoler, president of Louisville Public Media -- which runs the Kentucky Center for Investigative Reporting -- expressed sadness at his death and said it grieves for his loved ones.

A statement from Michael Skoler, President of Louisville Public Media. pic.twitter.com/abgbOaaxUD — Kentucky CIR (@KentuckyCIR) December 14, 2017

"Our aim, as always, is to provide the public with fact-based, unbiased reporting and hold public officials accountable for their actions," he said in a statement. "As part of our process, we reached out to Representative Johnson numerous times over the course of a seven-month investigation. He declined requests to talk about our findings."

Johnson's funeral service will be held Monday at the Heart of Fire Church.