On the 150th anniversary of "Juneteenth," the final freeing of slaves after the Civil War, the LDS Church announced Friday a project to emancipate from obscurity key records of about 4 million former slaves' families and lives.

The Utah-based faith digitized and now will lead efforts to index — for easy online researching by name — records of the Freedmen's Bureau, an agency Congress created at the end of the war to help the first generation of African-Americans experience freedom.

LDS apostle D. Todd Christofferson called on the nation's African-Americans to help with that project — and said many of their groups already have signed on. He said they will "potentially reunite the black family that was once torn apart by slavery."

Speaking in Los Angeles at the California African American Museum, he urged finishing the indexing of 1.4 million digitized records before completion next year of the new Smithsonian National Museum of African American History and Culture on the famed mall in Washington, D.C.

Indexing allows easy searches by name, date or place, enabling descendants to proceed directly to a document that mentions an ancestor. Otherwise, researchers would need to read every record to search for a familiar name.

"The black community is uniting to create a wonderful tool with which to discover its own family," Christofferson said. Information about the project and how to volunteer is available online at discoverfreedmen.org.

Christofferson said the records contain a treasure of genealogy and historical information.

"The bureau helped reunite families, opened schools to educate the illiterate, managed hospitals, supervised labor contracts, rationed food and clothing, and even formalized marriages. In the process, the bureau gathered handwritten information on African-Americans," he said. "These are personal, sometimes difficult accounts to read at a turning point in our nation's history when our forebears were struggling with their own humanity. But what one also sees in these records is triumph, hope and resilience. What a great testimony to the sheer will and determination of this generation."

Hollis Gentry, genealogy specialist at the National Museum of African American History and Culture, said, "These are the earliest of recordings of people who were formerly enslaved. We get a sense of their voice. We get a sense of their desires, their goals, their dreams, their hopes."

Thom Reed, marketing director at the LDS-sponsored FamilySearch International, the world's largest genealogy organization, said, "These records will open a window that we've never had opened before" and may reveal the lives of freed slaves in ways "similar to what the Rosetta Stone did" to decode ancient languages.

Reed said many African-Americans, including himself, have up to now "run into a brick wall" because it is difficult to find any genealogy before the 1870 Census, the first to list former slaves. He hopes to use the new records to find earlier generations.

Gentry said she did exactly that, and used the records to track several ancestors, including one that settled a town in Kentucky now named for him. It "helped me find details about their transition from slavery to freedom. I hope that will be replicated by all researchers who come to those records looking for details about their family."

"We are part of making history. This will change the fabric of genealogy for African-Americans," said Sherri Camp, vice president of the Afro-American Historical and Genealogical Society.

Jannah Scott, deputy director or the White House Office of Faith-based and Neighborhood Partnerships, thanked The Church of Jesus Christ of Latter-day Saints for buying, digitizing and now indexing copies of the records — calling it an act of affection coming two days after the hate shown in the Charleston, S.C., murders of worshipers at a black church.

"It is an act of love," she said.

It is not the first time the LDS Church has helped bring to light similar records. In 2001, it indexed and made available records of the similar-sounding Freedman's Bank, a separate organization that financially helped former slaves. It had only about a tenth the amount of records of the current project.

Christofferson said the church is involved in genealogy because it believes families are linked forever, and that knowing the sacrifices of ancestors helps those living now. Mormons also perform ordinances, such as baptism, on behalf of ancestors in LDS temples with the belief that those forebears can accept or reject them in the next life.

The LDS Church was a target of past criticism for not allowing black males to hold its priesthood. Mormon leaders lifted that ban in 1978, helping to spur rapid LDS growth in places such as Africa and Brazil.

At the church's Friday news conference, the hosts of the ceremonies were Jermaine Sullivan, a black Mormon who oversees a cluster of LDS congregations in Atlanta, and his wife, Kembe. They were featured in the 2014 film "Meet the Mormons."

The new project is a joint effort by FamilySearch, the Smithsonian National Museum of African American History and Culture, the Afro-American Historical and Genealogical Society and the California African American Museum.