Cause of Death Revealed for Paranormal Investigator Whose Body Was Found After Touring with ‘Possessed’ Annabelle Doll

A cause of death has been confirmed for the paranormal investigator who passed away in July after attending an event in Gettysburg, Pennsylvania, where the infamous Annabelle doll was showcased.

Dan Rivera, an Army veteran and senior lead investigator for the Connecticut-based New England Society for Psychic Research, died on July 13, one day after taking part in the event featuring the haunted doll that has long been tied to horror stories.

Francis Dutrow, the Adams County coroner, announced on Thursday, Sept. 4, that Rivera’s death was caused by heart-related issues and was ruled natural.

“Mr. Rivera had a known history of cardiac issues, which were consistent with the findings. It is also confirmed that Annabelle was not present in the room at the time of his passing,” Dutrow said.

According to a July 13 report from the Pennsylvania State Police, Rivera, 54, was discovered in his hotel room in Straban Township. “Nothing unusual or suspicious was observed at the scene,” the report noted.

Earlier that day, Rivera had been with colleagues but told them he wasn’t feeling well and returned to his room, Dutrow told PEOPLE. It wasn’t clear what illness he was experiencing.

Rivera was in Gettysburg as part of a tour featuring Annabelle, which the New England Society for Psychic Research describes as “demonically possessed.”

The society says Annabelle’s story goes back to 1968, when a nursing student received the doll as a gift. Soon after, the student and her roommate reported strange activity and learned through a medium that the doll was said to be inhabited by the spirit of a young girl named Annabelle. Attempts to live peacefully with the doll led only to fear and violence, according to the group.

Husband and wife Ed and Lorraine Warren, who founded the society, eventually took Annabelle from the home and secured her in a glass case “to contain the evil spirited entity.” The doll remains locked away today.

Annabelle and the Warrens later inspired The Conjuring film franchise.

Harrison Jones, a journalist with the Evening Sun in Hanover, Pennsylvania, attended the tour the day before Rivera died. He told PEOPLE that Rivera “definitely struck me as a kind and very welcoming person, and my heart breaks for his family and colleagues.”

Jones joined a group tour and captured photos and video as Rivera spoke about Annabelle’s history and his own work with the doll. Rivera even explained that he had built the case that houses Annabelle himself, designing parts of it with his faith in mind.

Although Jones did not spend much time speaking one-on-one with Rivera, he recalled that the investigator asked if he had gotten what he needed from the visit and whether he had captured good images.

The following day, Jones learned that Rivera had died. “It was clear from the prior controversy surrounding the tour that his death was going to immediately cause intense controversy and become his own part of paranormal legend no matter what was said,” he told PEOPLE. “But in my own reporting I was mainly concerned with trying to focus on the human life lost at the center of this tragic news, Mr. Rivera, who had dedicated so much time and effort in sharing his love for the paranormal.”

In a statement to PEOPLE, the New England Society for Psychic Research remembered Rivera as a “vital part of our team for over a decade, but also a deeply compassionate, loyal, and dedicated friend.”

The group added, “Dan’s passion for the paranormal was rooted in a genuine desire to educate, help, and connect with others — whether through social media, conventions, or investigations with local families seeking understanding and peace. We understand that Dan’s work inspired fascination and curiosity for many, but above all, he was a father, devoted husband, and loyal friend, someone who meant the world to those closest to him. Out of respect for his family, we kindly ask for privacy as they mourn this tremendous loss.”