(CNN) South Carolina authorities are investigating the historic African-American church that was targeted by a white supremacist in a 2015 massacre in Charleston, authorities say, but details are few.

While the nature of the probe is unclear, Emanuel African Methodist Episcopal Church's former secretary Althea Latham told The Post and Courier newspaper she had spoken to South Carolina Law Enforcement Division investigators about donations the church received after the shooting.

Church historian Liz Alston told the paper she, too, had spoken with SLED agents.

SLED spokesman Tommy Crosby confirmed to CNN that an investigation is under way, but "as it is an open case, I am unable to provide any specific details at this time," he said in an email.

Emanuel senior pastor Eric Manning, who took the church's helm about a year after the shooting, said he was not aware of any investigation.

"We have not spoken with SLED and don't know where this is going, but we look forward to hearing from them," he told CNN.

The donations that Latham reportedly discussed with SLED were the subject of a wrongful termination lawsuit she filed against the church in 2016. It was jointly dismissed last year, court records show.

Attorney Andy Savage, who represents three of the shooting survivors and five of the slain victims' estates, said he has been critical of the church's processing of more than $3 million in donations.

He declined to comment on the scope of SLED's investigation but confirmed that more than one of his clients had spoken with SLED agents or made information available at the agency's request.

Questions about transparency

On June 17, 2015, a white supremacist attended a prayer meeting at the 201-year-old church , known as Mother Emanuel, spending about an hour with parishioners before opening fire and killing nine of them. Found guilty of murder and hate crimes, the gunman now sits on federal death row

Charitable souls the world over opened their checkbooks. According to Savage and The Post and Courier's reporting , the church kept about $1.8 million in donations for building maintenance, an endowment, a memorial and scholarships.

The remaining $1.5 million was split among the victims' immediate families and one of the survivors, Savage said.

Families were upset that the church kept more money than it doled out to the victims, Savage said.

In Latham's 2016 lawsuit, the former church secretary alleged that she was fired after telling Emanuel leaders it was illegal to open letters -- some containing cash and checks -- that were addressed to the victims. The church denied the allegations, but later paid an undisclosed settlement and both parties agreed to dismiss the case last year, Latham's attorney, Bruce Miller, said.

Savage heard from victims' relatives that about a year after the shooting, church staffers delivered sympathetic letters to families, which were addressed to them but had already been opened. In other cases, the envelopes contained nothing, and someone had written "empty" on them, he said.

"It's just suspicious," he said.

While Pastor Manning declined to comment further on the SLED probe, he did address the allegations of church staff absconding with donations, telling CNN affiliate WBTW in 2016 that he was working through "some of the past challenges" at the church. All donations had been handled carefully since he became senior pastor at Emanuel, he said.

"I do believe in being open and transparent — open and honest with everything that we do regarding finances," he told the station.

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Savage would not divulge the nature of SLED's questions for his clients, but he said families felt that Mother Emanuel's leaders took the position that the donations flowing into the church after the shooting were "sent for the benefit of the church, that the church was the victim.

"Well, that's not how I felt about it, and many others felt the same way," he said.

Savage said he doesn't believe mourners donated so generously for the church to cover its own expenses. Rather, the attorney said, he believes donors wanted to take care of the victims.

Attorney: Young survivor remains traumatized

Church leaders said most of the donations were sent to Emanuel with no restrictions, while donors had earmarked $280,000 for the families, The Post and Courier reported in 2016 . The church added more than $1 million to the family's sum, it said.

Emanuel AME used a formula similar to the one the city employed when it divvied up millions in Hope Fund contributions among the families, but the church included more family members "to broaden the reach of the donations," church attorney Wilbur Johnson told the paper.

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Each of the nine victims' immediate families received $150,000. Polly Sheppard, who the killer let live to relay the story of the massacre, also received $150,000, Savage said.

But Felicia Sanders -- who played dead, shielding her granddaughter as the gunman claimed nine lives, including her 87-year-old aunt and her 26-year-old son Tywanza -- received compensation only for her son's killing, Savage said.

The attorney is representing several plaintiffs -- including Sheppard, Sanders, her granddaughter and Sanders' aunt's and son's estates -- in a lawsuit against the US government. It alleges the FBI's background check system failed to flag the 21-year-old Charleston killer's felony drug arrest, which would have prevented him from buying the Glock 41 he used in the slayings, court documents indicate.

The government has claimed immunity, but a federal appeals court disagreed, and the case will be sent to back to US District Court for South Carolina unless the government appeals the decision, records show.

Savage has been "urging the church to compensate Felicia and her granddaughter, as they have been victimized every bit as much as the other survivors," he said.

Of special concern, Savage said, is Sanders' granddaughter, who was 11 at the time of the shooting.

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She has required extensive therapy and medical treatment, including spells in the hospital, the lawyer said. The damage to her psyche is profound, he said.

Her family lacks the means to pay for the therapy she requires, but church leaders have demonstrated a sense of entitlement that "just flies in the face of what happened to these two survivors," the attorney said.

"The 11-year-old, at least in terms of medical care, is the one who has been harmed the most," Savage said. "Her medical bills are just out of this world ... How the church could just turn a blind eye to that is beyond me."