Thomas Markle Sr, the estranged father of the Duchess of Sussex Meghan Markle, was arrested in Florida on Friday.
Markle, 82, is charged with one count of "possession of child pornography" and is to make an initial court appearance in Tampa on Friday, US Attorney Bill Essayli said in a statement.
RelatedThe arrest follows an investigation launched after Markle's son, Thomas Markle Jr, reportedly discovered boxes containing hundreds or potentially thousands of images at his father's former home in Cebu City, in the Philippines.
Markle Jr alerted Philippine police and contacted the US Federal Bureau of Investigation (FBI), prompting authorities in both countries to examine the allegations.
Authorities said Markle allegedly "kept child sexual abuse material (CSAM), including sexually explicit photographs of himself with prepubescent girls, in two Los Angeles-area storage units he rented for nearly two decades."
"Inside the units, agents seized approximately 78 items, including slides, film negatives, and books that contained suspected CSAM," it said.
Markle could face up to 20 years in prison if convicted of possession of child sex abuse material.
Thousands of images uncovered in the Philippines
Philippine authorities have reported recovering around 7,500 photographs and one video depicting underage children from electronic devices linked to the investigation.
Interior and Local Government Secretary Jonvic Remulla said some of the children appeared to be as young as 10 or 11.
According to Philippine police, an initial forensic examination identified suspected child sexual abuse and exploitation material on several storage devices. Investigators have stressed, however, that the findings do not yet establish who owned, produced or distributed the material.
The FBI has been cooperating with Philippine authorities as investigators seek to establish the ownership of the devices and determine whether further individuals were involved.
Markle, 82, has previously denied possessing child sexual abuse images and rejected the allegations against him.
The investigation has also expanded beyond the Philippines, with reports of a separate cache of material allegedly linked to Markle being examined in Mexico.
Meghan says she was 'deeply distressed'
Meghan, the Duchess of Sussex, recently broke her silence over the allegations, saying she was "deeply distressed" by the reports and expressing concern for any children who may have been harmed.
In a statement, she also revealed that a letter containing what she described as "troubling and disturbing allegations" about her father had been sent to London's Metropolitan Police in 2018 and subsequently shared with her.
Meghan said she had been assured that the allegations were being investigated.
She also addressed her long-standing estrangement from her father, saying her decision to prevent him from having contact with her children, Prince Archie and Princess Lilibet, was intended to protect them.
The Duchess married Prince Harry at Windsor Castle in May 2018. Her father, a retired television lighting and photography director, did not attend the wedding after a highly publicised family dispute.
Meghan's half-brother also under scrutiny
The investigation took a further turn on Thursday after Philippine authorities named Thomas Markle Jr as a person of interest in the inquiry.
Remulla said investigators were examining information suggesting that underage girls may have visited Markle Jr's home in Cebu. He stressed that the 60-year-old was not being treated as a suspect.
Markle Jr was the person who initially reported the alleged images to authorities. His possible involvement is being investigated separately from the discovery of the material, according to reports.
A family dispute played out in public
The development has added another layer of complexity to the case, which now involves investigators in the Philippines, the United States and potentially Mexico.
The arrest brings renewed attention to the long-running family rift between Meghan and her father.
Markle Sr returned to the United States earlier this year after suffering a stroke and undergoing the amputation of his left leg while living in the Philippines.
His relationship with Meghan deteriorated in the run-up to her 2018 wedding to then-Prince Harry. Prince Harry stepped back from his role as a senior working member of the British royal family in 2020, giving up his official royal duties alongside Meghan.
