The murder of an elderly couple in their Jerusalem apartment on Jan. 13 appears to have been terrorism, the Hadashot evening news reported on Tuesday. Investigators have reportedly made a breakthrough in the case, but the details are still under a court-issued gag order.

Yehuda and Tamar Kaduri were found dead in their apartment on Sunday after family members said they had been unable to contact them for days. Forensic teams concluded that the two were violently murdered, most likely on Friday, but were unable to determine a motive.

The Kaduris’ apartment is in Armon Hanatziv, a neighborhood in Jerusalem in close proximity to an Arab neighborhood, and on the same street where a stabbing attack took place earlier last week.

In recent days police have been interviewing friends and neighbors, who shed some light on the couple

“Yehuda was such a friendly person, he had so many friends,” his sister Rachel said on Tuesday. “After our father died he became religious and we stopped seeing him that often. Tamar was the daughter of Holocaust survivors … she also witnessed several terrorist attacks and as a result, her psychological state deteriorated,” the sister continued.

Neighbors said that a day before the murder they heard screams coming from the apartment.

“We have pangs of conscience for not going inside; we feel so sad, and we have had trouble sleeping since,” said a neighbor. “Tamar was like a daughter to us; she was a frequent visitor at our apartment for 40 years.”