Nearly a decade after Liliana Moreno and her 8-year-old daughter Daniella disappeared in the Miami area, federal investigators say they have now arrested a man in the case: the girl’s father.

Gustavo Alfonso Castano Restrepo, 55, of Miami was arrested Monday, days after he was indicted in federal court on a charge of kidnapping resulting in death in connection with the 2016 disappearances of Liliana and Danielle. court documents show.

But much of the case remains shrouded in mystery to the public and to Liliana’s family: Although the two-page indictment filed in U.S. District Court in Miami charges him — accusing him of kidnapping Liliana, then 42 — claims that the kidnapping resulted in the death of both Liliana and the child. Authorities have released very few details, including why investigators believe they are dead, how the abduction occurred, what led them to arrest Castano and whether they know a motive.

The claim in the indictment that Liliana and Daniella are dead “is not what we want to see,” Liliana’s brother, Eduardo Moreno, told CNN this week.

“We as a family … are trying to find out what happened,” he told CNN by phone.

The mother and daughter, who lived in Doral, northwest of Miami, were last seen at or near a Home Depot in nearby Hialeah on May 30, 2016, according to the FBI.

Castano is Danielle’s father, though “he was never involved in Danielle’s life,” Eduardo Moreno told CNN.

Liliana and Castano also met through their careers, her brother said. Liliana was an architect, Castano was in construction, and they had worked together often, the Miami Herald reported.

The U.S. Attorney’s Office for the Southern District of Florida announced the indictment on Tuesday. Castano remained in custody following a hearing before a federal federal judge that day, the office said.

Court documents and the office’s press release did not say whether investigators found Liliana or Daniella dead. The indictment alleges that Castano kidnapped Liliana, held her “for reward and otherwise” and used “a cell phone, the Internet, a motor vehicle and the Homestead Extension of Florida’s Turnpike” in the commission of the crime.

“It is further alleged that the commission of the aforesaid kidnapping resulted” in the deaths of both Liliana and Daniella Moreno, the indictment said, without elaborating.

The FBI — one of the agencies investigating the case, according to prosecutors — cannot discuss ongoing investigations like this one, said spokesman Jim Marshall, who pointed to court documents and the U.S. attorney’s press release as available information. The Miami-Dade Police Department, another agency involved in the case, did not respond to CNN’s request for comment.

CNN reached out to the U.S. attorney’s office with questions about the case, but did not immediately hear back.

An attorney for Castano, Phil Reizenstein, told CNN on Friday that he had just been retained in the case and needed time to investigate, prepare and put together a bond proposal. His office plans to request a detention hearing Wednesday, he said.

If convicted, Castano would face a mandatory minimum sentence of life in prison, the U.S. attorney’s statement said. The maximum penalty would be death, the office said.

The disappearance

Eduardo spoke to his sister on the phone less than an hour before he left her home on May 30, 2016, he told CNN. He did not say why he left the house, but added that Liliana’s intention was to stay at home most of the day.

That day was also the birthday of their sister Carolina, who lives in Colombia with much of the rest of the Moreno family, he said.

“They always called her (Carolina) on her birthday,” Eduardo said. But Liliana and Daniella didn’t call Carolina that Monday.

That’s when her family started to worry.

Eduardo, who was in Colombia at the time, said the family received a call from Castano on the morning of May 31 asking if they had heard from Liliana. During the call, Castano wavered on whether he last saw Liliana on May 30 or a few days before, Eduardo said.

Becoming concerned about his sisters’ whereabouts, Eduardo asked a friend of Liliana’s who lives in Doral to check on his sister’s house to see if she was there, he said.

“We assumed Liliana’s car wasn’t at her house because Gustavo told us he looked for Liliana’s car and it wasn’t there,” Eduardo said. But Liliana’s friend said her car was parked in the same place it was usually parked and no one was home.

Eduardo then decided to involve the police.

At Liliana’s home, police saw her car in the driveway and food on a stove and also found her wallet, CNN affiliate WPLG reported.

The FBI’s missing person poster for the mother and her child says they “are believed to have been last seen at or near the Home Depot located at 13895 Okeechobee Road in Hialeah, Florida.” According to WPLG, Castano told police that Liliana requested that she and her daughter be dropped off on the Florida Turnpike at Okeechobee Road — an intersection very close to Home Depot.

“We want to know what happened,” Eduardo Moreno told CNN. “If something happened to my sister Liliana, where is Daniella?”

“In this case, it’s more about finding out what happened or at least trying to bring them back,” he said.

CNN’s Amanda Musa contributed to this report.

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