(CNN) -- Adam Mayes -- accused of murder and kidnapping in a case involving a Tennessee mother and her three daughters -- has died, said FBI spokesman Joel Siskovic. The two sisters he allegedly kidnapped were found alive, law enforcement sources said.
There had been conflicting reports about Mayes' fate since he was found after suffering an apparently self-inflicted gunshot wound Thursday night in Union County, Mississippi.
The two surviving sisters "are suffering from the experience of being out in the woods and from being kidnapped. They are suffering from dehydration and exhaustion, but appear OK," a federal law enforcement source on the scene told CNN.
Mayes, 35, was suspected of abducting Alexandria Bain, 12, and Kyliyah Bain, 8, from their Whiteville, Tennessee, home, in late April, and killing Jo Ann Bain and her eldest daughter, Adrienne, 14.
A law enforcement source confirmed to CNN that a SWAT team surrounded a patch of woods in Union County.
At that point, when they were mobilizing, officers heard a single gunshot.
Adam and his wife, Teresa Mayes, each were charged with two counts of first-degree murder and two counts of especially aggravated kidnapping. He faced an additional count of making a false report, according to arrest affidavits filed in Tennessee.
Adam Mayes' mother-in-law told HLN's Nancy Grace that he may have believed he was the father of the two young girls he was accused of abducting.
"He believes they are his children," Josie Tate told Grace.
Tate, who lives in Chatsworth, Georgia, earlier Thursday tearfully pleaded for Mayes to return Alexandria and Kyliyah Bain and turn himself in.
"You've had a chance to live life. They haven't," Tate said. "Give them that chance."
In affidavits, investigators said the Mayeses drove the bodies of Jo Ann and Adrienne Bain to Union County in northern Mississippi, where they were discovered Saturday in a shallow grave behind the house of Adam Mayes' mother in Guntown, Mississippi.
Adam Mayes' mother, Mary Frances Mayes, has been charged with four counts of conspiracy to commit especially aggravated kidnapping.
Adam Mayes was last seen May 1 in Guntown. While the search was centered around his hometown, he also has connections to Arizona, Texas, Florida and the Carolinas, the FBI said.
The FBI on Wednesday put Adam Mayes on its list of 10 most wanted fugitives. The reward for information leading to Mayes' arrest stood at $175,000 on Thursday.
Bobbi Booth, Mayes' sister-in-law, told CNN's Anderson Cooper on Thursday night that she's "overwhelmed right now."
"All I'm (thinking) about now is that the children are safe," said Booth. "Thank you, God, for letting those children come home."