David Pichosky, 71, and Rochelle Wise, 66, of Toronto were found dead of asphyxiation on Jan. 10, 2013, in their Hallandale Beach home, and police say their bodies were bound.
The DNA profiles of two females were found at the crime scene, which is unusual, said Police Chief Dwayne Flournoy.
They did not match DNA in a databank of profiles collected by law enforcement agencies, nor did it match any profiles in Canada's national DNA databank, he said.
"The science tells us that there are two females that are involved in this homicide — at least two," he said Wednesday at a news conference.
"It's only a matter of time before we get our match, and we will get our match."
The DNA profiles also do not match anyone in the Pichosky or Wise families or anyone who would have had access to the couple's home, such as workers, housekeepers or maintenance crews, Flournoy said. The two profiles are not related to each other, he said.
The killings may have been motivated by robbery, police have said, as Wise's wedding band — valued at $16,000 — was the only thing missing from the couple's condo. Flournoy described it as white, with five diamonds and a half-shaped moon.
It was also designed with a special clasp to accommodate Wise's arthritis, he said. Searches of local pawn shops and jewellers have not turned up the unique ring, he said.
But police still do not know why the well-liked couple was apparently targeted, Flournoy said. Pichosky and Wise had no enemies, were not flashy and did not carry around large sums of money, he said.
"So we just have not been able to pinpoint the reason why someone would either target them, or was it a crime of opportunity?" Flournoy said. "I think it's more likely that they did not know their attackers."
Members of Pichosky and Wise's families were on hand for the news conference and appealed for anyone with information to come forward.
"Over the past 12 months we have learned to live in a new reality. The sun comes up, the birds may be singing, but for our family every day is a nightmare," said Pichosky's daughter, Sari Rosenblum.
"We have no peace, we have no closure, we have no understanding of why this has happened. I still have nightmares. I can't put aside what happened to them and have no chance of moving on. Nothing in our lives is normal anymore."
The couple's marriage — the second, for each of them — was their second chance at love, Rosenblum said. They loved each other and in turn were well-liked in their Toronto and Florida communities, the family said, adding that 1,500 people attended their funeral.
Pichosky made weekly visits to the elderly and the sick in Toronto and would telephone them weekly from Florida, his daughter said. In Florida, Wise volunteered once a week at a Hebrew academy teaching children who needed remedial help, her friend Pearl Gladman said.
Despite the amount of time that has passed since the deaths, police are still waiting for some lab results, the chief said.
Investigators collected an "inordinate" amount of evidence and the lab processed it in three rounds. Police are waiting for the results on the final round, Flournoy said.
Police have not yet been able to identify a woman seen on surveillance video walking around the couple's home the morning police believe they were killed, but she may hold the key to solving the double homicide.
"We believe that identification of this female is critical and important to this case," Flournoy said. So far, no one in the close-knit community has been able to identify her.
"With her being in and around the home and with two female DNA profiles being inside of the crime scene, she's particularly someone that we want to speak with."
A partial shoe print that was found at the scene has been identified as an Adidas shoe out of production since 2000. The largest model of shoe that sole was used on was the Supernova, Flournoy said. Investigators were not able to determine its size, nor whether it was a man's or woman's shoe, he said.
Private donations have now increased the reward offered through Broward County Crime Stoppers to US$57,000, Flournoy said. He vowed to the family that the killers would be found.
"I told you guys we're going to solve this case, right?" he said. "We're going to solve this case."
— by Allison Jones in Toronto