Less than a year after prominent Christian apologist Ravi Zacharias’ death, the US-based organisation he founded has confirmed allegations of sexual misconduct made against him.

The board of directors’ executive committee at RZIM this week said that preliminary results from an investigation had confirmed allegations that Zacharias had abused workers at two spas that he co-owned.

The abuse by the influential spiritual leader spanned years and may go beyond those spas, the RZIM statement said.

According to a September 29 article in Christianity Today, three women, who worked at locations in metro Atlanta, claimed that Zacharias had touched them inappropriately and exposed himself during regular treatments. Details of the allegations by the women have not been made public.

The investigation is ongoing and a final report is not expected until early next year, according to RZIM.

“Sadly, the interim investigation update indicates this assessment of Ravi’s behaviour to be true – that he did indeed engage in sexual misconduct,” according to the statement.

“This misconduct is deeply troubling and wholly inconsistent with the man Ravi Zacharias presented both publicly and privately to so many over more than four decades of public ministry,” RZIM said.

“We are heartbroken at learning this but feel it necessary to be transparent and to inform our staff, donors, and supporters at this time, even while the investigation continues. We will speak more comprehensively to all concerned after the completion of the investigation,” it said.

The organisation also addressed those hurt by Zacharias’ action, saying it was devastated for those who have suffered from his “misconduct and for the pain that they are enduring”.

Zacharias, head of a global ministry and bestselling author, died in May at his home in Atlanta, following a brief battle with cancer. He was 74.

The Chennai-born preacher spent nearly five decades addressing questions of origin, meaning, morality and destiny. As a Christian apologist, Zacharias defended religious doctrine and philosophy.

He was a close friend of the late evangelist Billy Graham and among those who spoke at his memorial service was Vice-President Mike Pence.

RZIM said that in August this year – three months after his death – that allegations of sexual misconduct were made against its founder. It hired the Atlanta law firm of Miller & Martin to investigate the allegations.

Lawyer Lynsey Barron of Miller & Martin said the firm would not comment beyond the letter to RZIM.

The organisation decided to address the allegations publicly earlier this week, following an interim investigation update. The report did not identify his accusers.

The website included a copy of the interim report. According to the report, investigators spoke with therapists who had treated Zacharias from the Touch of Eden and Jivan Wellness spas as well as others who treated him over the years. They also reviewed documents and electronic devices used by Zacharias.

RZIM is calling for any other potential victims to come forward. RZIM was founded in 1984 and has a worldwide reach, with offices in places including Britain, Latin America, India, Singapore and Hong Kong.

Zacharias discovered his calling aged 17, after trying to take his own life by swallowing poison. He survived and turned to the Bible while recovering in hospital.

During the 1970s, Zacharias spent time in Vietnam where he evangelised to both US soldiers and imprisoned Viet Cong members. Later, he travelled to Cambodia, where he preached before it fell to the Khmer Rouge.

Some years after founding RZIM, Zacharias expanded into academia, launching the Veritas Forum, hosted on the campus of Harvard University. In 2004, he established the Oxford Centre for Christian Apologetics at Oxford University, where he was an honorary senior research fellow between 2007 and 2015.