When the Bureau spoke to personnel from the girls' school, he recalled, "they were utterly shocked." The sisters—especially Faloma—were known for their pleasant demeanors and constant smiles, he noted.

"People want to find out what happened to these girls," Park said. "They want to bring these girls back."

At the time of their disappearance, 9-year-old Maleina stood about 4' tall, weighed about 65 pounds, and had a birthmark on her left cheek. She has brown hair and brown eyes and was last seen wearing a white blouse and blue jeans. Her birthday is February 13. You can view Maleina's Missing Person poster to learn more about her.

Ten-year-old Faloma stood about 5'1" tall and weighed about 90 pounds. Like her little sister, she has brown hair and brown eyes. She was last seen wearing a light green shirt with a butterfly design and blue jeans. Her birthday is February 9. You can view Faloma's Missing Person poster to learn more about her.

On this episode of the Inside the FBI Podcast, we’ll discuss the 2011 disappearance of Maleina and Faloma Luhk, why the FBI is still determined to find them, and how you can help us solve this case and bring closure to their family and their community. Transcript | Download Audio

Searching for the sisters

The FBI has been investigating Faloma and Maleina's disappearance since May 25, 2011.

The Bureau has legal jurisdiction to investigate federal crimes in U.S. territories like the Commonwealth of the Northern Mariana Islands (or CNMI), where Saipan is located. The FBI's Honolulu Division even has a satellite office on Saipan.

Since May 2011, federal agencies including the U.S. Marshals Service, the Drug Enforcement Administration, and the Department of Homeland Security have partnered with the FBI and CNMI authorities to search for the girls.

The local community also played a major role in the early part of the investigation, helping scour Saipan's unique terrain for signs of Faloma and Maleina. "We had law enforcement officers and government agencies flying to Saipan to support us, but it took people on the ground to help us look further into the jungle, where they knew the land, they knew the woods, they knew the back jungle, back beaches," Park said.

The FBI has also searched the waters surrounding Saipan and conducted aircraft and seafaring vessel inquiries—since the island is only reachable by air or sea—for signs of the girls.

Unfortunately, these exhaustive efforts and extensive witness interviews haven't yielded any answers.

"There is no conclusion to where these girls might've ended up," Park said. "Our hope's we find these girls alive somewhere."

The girls' disappearance has profoundly impacted Faloma and Maleina’s families and community, investigators said. "They left a big hole in a lot of people's hearts, left a lot of questions unanswered," Park said.

The incident also shattered Saipan’s reputation for being a safe place for children to roam. "It's a very loving community, and that is why it was so detrimental when this occurred, because that safety was snatched from the community," said FBI Special Agent Rick Bauer, who's currently leading this case for FBI Honolulu. "That's just another reason to drive us and the law enforcement—and the community—to get answers."

Looking for clues on the 'coconut wire'

Investigators say additional clues in this case may come from across an ocean.

A large number of Micronesians have migrated to the continental United States—mainly to the Pacific Northwest, but also to states like Idaho and Texas. Since the Micronesian community's bonds are strong, a steady flow of individuals in the diaspora travel home to attend annual community events. Likewise, Saipan residents frequently travel to the continental U.S. to visit friends and loved ones.

Chatter between current and former Saipan residents naturally ensues—a phenomenon Park said is known as the "coconut wire." And, he said, "news travels fast." For this reason, the FBI is also asking anyone who might’ve heard information about Faloma and Maleina's whereabouts through the grapevine—on either side of the Pacific Ocean—to come forward.

"We want to reach out to those Micronesians that might have been here during that time or heard something," he said. "We want to see if they want to come forward, help us, help the family, bring closure, or give us some evidence that we can use."

If you have any information about Faloma and Maleina's whereabouts or what might’ve happened to them—even if you've already spoken with law enforcement about the case—we encourage you to contact the FBI.

You can submit tips by phone at 1-800-CALL-FBI (1-800-225-5324) or online at tips.fbi.gov. Tips may be shared anonymously, and no detail is too small to potentially help investigators solve this case.

"We believe there are people out there that know something," Bauer said. "No matter how big or how little it may be, it could be something that law enforcement can use in solving this mystery."