"With the help of God, I hope Nassau police can conclude this investigation," said Anton Weiss, father of slain rabbinical student, Chaim Weiss.
Weiss, 15, was found stabbed multiple times in his dorm room on East Beech Street in Long Beach on Nov. 1, 1986. No one has been arrested in connection with the murder.
After a review of the nearly three-decade-old case, Nassau police decided to reopen the investigation. Nassau Crime Stoppers has increased the reward for information leading to an arrest from $5,000 to $25,000.
"There's somebody out there that knows a secret. I'm looking for that person to give me that secret," said Detective Lt. John Azzata, commander of the Nassau police homicide squad.
Tips have already begun to flow to investigators, police said. Investigators are looking to interview any student, faculty member or employee connected to the Torah High School, which Weiss was attending.
Weiss' father urged his son's former classmates, now adults and parents, to help bring the killer to justice.
"I am appealing to you in the strongest way," Anton Weiss said.
"I ask you, I urge you to please contact the police department."
One problem police face in the hunt for Weiss' killer is the reluctance of members of the Orthodox Jewish community to speak directly to local authorities, according to Rabbi Shmuel Goldin of the Rabbinical Council of America.
Goldin urged community members to cast that tradition aside, insisting that it is the "obligation" of everyone to help solve the Weiss case.
"The Mesivta of Long Beach applauds the perseverance of the Nassau Police department," said a statement from Weiss' school.
"We encourage all who have relevant information that could prove useful to the investigation to extend their full support."
Investigators are unclear if someone connected to the Long Beach yeshiva was involved in the murder.
There was no sign of forced entry in Weiss' room, but there were clues, police said, which indicate the killer was familiar with Orthodox Jewish traditions.
Among those clues was a window left open to "allow the victim's soul to escape," according to Det. Lt. Azzata.