After meeting with the father and mother of the four children, their bodies were discovered in a New York apartment, several days after the meeting.

A Utah father was days away from meeting his four children, the culmination of years of visits, when he learned that his children had been killed in a heinous crime allegedly committed by their grandmother.

Brady Harmon said she picked up her children Wednesday and plans to return them to their mother in New York on Sept. 1 as part of a court-ordered parenting plan. Instead, Salt Lake City Police said his children Harper Harmon, 13, and Hudson Harmon, 11. and 10-year-old twins Gavin and Gracelyn Harmon were found dead in an apartment in Mechanicville, New York.

The children’s mother, Sarah Myers, 44, and maternal grandmother, Amy Stedman, 64, were also found dead, Mechanicville police said.

Officers were dispatched to the apartment after a neighbor reported not seeing Steadman in a while. Police Chief William Rabbitt said at a news conference Thursday that Stedman lived in the apartment, and Myers and the children lived separately in the same building.

“I don’t know what happened,” Harmon said in a phone interview Friday. “There’s speculation, but not being able to see the kids, that’s the biggest disappointment.”

Mr Rabbitt said one of the children appeared to have sustained fatal injuries from the sharp impact. The evidence also points to intentional poisoning, including what he described as “numerous prescription and over-the-counter drugs.” The cause and manner of death of all six victims is pending further examination.

A handwritten note found in the apartment “strongly implicates Amy Stedman in the death,” Rabbitt said, declining to say what the note contained.

Harmon said he learned of Stedman’s role after watching the press conference. “I don’t know how they could think it was her,” he said. “The handwritten note, that’s a different matter, but she had nothing to lose or gain if the kids came here.”

Harmon said she has been fighting for visitation rights for years. The couple separated in November 2019 and their divorce was finalized the following year, according to court documents obtained by NBC News. After the separation, Myers moved to New York with his mother and children.

Under the custody agreement, Harmon had the right to visit the children from July to September, in addition to regular FaceTime calls. But Myers repeatedly blocked both, he said. The last time he met his children in person was in 2019.

“There was always something going on and she found a way to get out of it,” he said. “We ended up having to hire another attorney just to implement the parenting plan.”

During the allowed FaceTime calls, Harmon said she was able to talk to all four children for about 15 minutes together if Myers was in the room.

He recalled small, everyday moments when Gavin was showing off something he’d made, or Gracelyn and Harper were sharing a painting they’d done for him.

Myers said she never thought anyone would harm her children and that in recent months, Myers seemed consistent and respectful of the parenting plan. Myers was scheduled to appear in court in Utah on Monday, according to separate court documents. Harmon said they were supposed to discuss a parenting agreement before having the child.

“Nobody can prepare for this,” he said.