The Son of Two Slain Billionaires Wants Answers, Ups Reward to $35 Million Barry and Honey Sherman were found strangled five years ago and their murders still remain unsolved.

It's been five years since Canadian billionaires Honey and Barry Sherman, who founded generic drug company Apotex, were found strangled to death in their Toronto home — and their family hasn't stopped looking for answers to their unsolved murders.

Ahead of the five-year anniversary of their untimely death, the Sherman family is upping the ante for information about their murders by $25 million. After previously offering $10 million, the reward now sits at $35 million for anyone who can spare details about the case.

"Closure will not be possible until those responsible for this evil act are brought to justice," the victim's son, Jonathan Sherman, said in a statement to CBC Toronto.

"My parents deserved to enjoy the fruits of their labor, and spend their twilight years as any grandparent should, with their family," Sherman added. "I continue to miss my parents more than I can describe, and I am forever haunted by what happened to them."

The investigation into the billionaires' deaths is still ongoing after they were found with belt loops around their necks and attached to a pool railing in December 2017, per The Guardian.

Their deaths were ruled a double homicide, and despite Toronto Police releasing video footage of someone walking outside of their home the day before the couple was killed, no suspects have been identified in the case, according to the BBC.

Although police claim they have received 1,255 public tips, conducted at least 250 witness interviews, and obtained 41 warrants, per BBC, Jonathan Sherman and his three other siblings have criticized the handling of their parents' case, and have hired an outside private investigator to look into the murders.

Ahead of their untimely deaths, Barry Sherman was chairman of the board of his Apotex drug company, while Honey Sherman was involved in philanthropic efforts.

According to CBC, Barry was involved in numerous legal issues, and his company was allegedly facing financial hardships after losing a $500 lawsuit.

Barry and Honey Sherman's net worth was estimated to be around $5 billion to $10 billion.