As a child, Julian Ako would visit his maternal great-grandfather’s home near Pilaa Beach in Kauai, Hawaii, where he and his family would gather edible fungi that grow on kukui trees and collect seaweed and fish from the reef.

For about a decade, that land has belonged to Meta CEO Mark Zuckerberg, who is constructing a massive compound at an estimated cost that exceeds $300 million. WIRED can now reveal that Zuckerberg’s property is atop a burial site: Ako’s great-grandmother and her brother were buried on the land.

After months of discussions with a Zuckerberg representative, Ako was successfully able to gain access to the property and identify and register the graves with the state Department of Land and Natural Resources, though he was not able to locate remains of other ancestors, who he believes could be buried on the property. In a report shared with WIRED, the state agency also confirmed “the probability (based on oral testimony) of additional burial sites.” Visits to Ako’s family’s graves are coordinated by the team at the Zuckerberg ranch. Ako, who sits on the Oahu Island Burial Council, worries about what might happen if further burial sites are discovered, because of the extreme secrecy surrounding the compound.

While NDAs are not unusual on billionaire construction projects, the scale of Zuckerberg’s compound has resulted in scores of local workers being forbidden from sharing what they’re doing and who they’re working for. “If all of the workers have signed these nondisclosure agreements, then basically they’re sworn to silence,” Ako says. “If they uncover iwi—or bones—it’s going to be a challenge for that to ever become public knowledge, because they’re putting their jobs in jeopardy.”

Asked about these burials, Zuckerberg representative Brandi Hoffine Barr acknowledged that the estate had been made aware of the family burial plot in 2015, which Hoffine Barr says they fenced off and maintained. She adds that their workers are bound by regulations that require reporting of inadvertent discoveries of iwi.

Meanwhile, Zuckerberg has quietly expanded his footprint on the island with a massive new land purchase, WIRED can reveal. Earlier this year, Zuckerberg purchased 962 acres of prime ranchland under a Hawaiian-sounding LLC across the road from the existing compound, which one person close to the sale estimated cost more than $65 million. This purchase, previously unreported, will increase his Kauai holdings from about 1,400 to more than 2,300 acres—placing him among the largest landowners in the state.

Development inside the ranch continues, as Zuckerberg has spent millions adding several new strange buildings to an already massive compound.Not far from Ako’s fishing spot, Zuckerberg has commissioned another three major buildings on previously purchased land. According to planning documents released to WIRED under a new public records request, they range in size from 7,820 to 11,152 square feet—nearly 10 times larger than the average home in Hawaii—and two are projected to cost between $3.5 and $4 million each.

These new buildings differ from the opulent mansions on the other side of the ranch, with few fun amenities and only one dedicated common space, a lanai larger than 1,300 square feet. Two of them seem designed to accommodate as many bedrooms and bathrooms as possible, and feature 16 of each between them, lined up like a motel or boarding house. As always, security is tight — with each new property featuring cameras, keypad locks, and motion detection devices. Hoffine Barr described these new buildings as short-term guest housing for family, friends, and staff.