Could a mystery Hollywood neighbour aid probe into Canadian's brutal 1969 killing?

Amid the many questions that still swirl around the brutal and unsolved killing of a young Canadian woman in Hollywood in 1969, there is a new one: Could someone named M. Lindhorst shed light on Reet Jurvetson's death?

Jurvetson, originally from Montreal, was 19 when she left her Toronto home, headed to Los Angeles to visit a friend known only as Jean. She was killed shortly after arriving, though her body wouldn't be identified for decades.

For 46 years, the L.A. Police Department knew her only as "Jane Doe 59" a woman found stabbed 157 times and dumped on the side of Mulholland Drive.

• Sketch shows 'person of interest' in woman's killing

• Police learn where woman stayed in Hollywood before death

For several months, CBC's the fifth estate has been telling Jurvetson's story via Instagram and Twitter and appealing for clues in the case.

The program recently discovered that in 1969, someone with the last name Lindhorst was living across the hall from the apartment where Jurvetson was staying with Jean, a young man also from Montreal.

None of Jurvetson's friends know Jean's surname and he is considered a person of interest by the LAPD.

In an interview with the fifth estate in May, the Los Angeles Police Department's lead detective in the case, Det. Louis Rivera, said: "The location where she was staying is the most important [lead] because from the location where she was staying, we can actually develop other leads because this was an apartment building.

"So Jean may not be around, but we're going to go and ask anyone who might have been there during that time period."

The LAPD hasn't yet been able to track down a single former neighbour.

It's been tricky because the building where Jean and Jurvetson stayed the Hollywood Executive Apartments was torn down in 1989. The last owner of the four-storey structure that backed onto Paramount Studios, Jack Dardashti, died in 2015. It is unknown what he did with the tenant records from his property.

• the fifth estate: Who killed Jane Doe #59
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However, the fifth estate has discovered that in 1969, a person named M. Lindhorst lived in apartment 305, directly across the hallway from the unit where Jurvetson and Jean stayed.

It is not clear if M. Lindhorst is a man or a woman or is even still living.

Despite the LAPD's public appeal for anyone who lived in or worked in the apartment building to step forward, no one has.

The Hollywood Executive Apartments had 64 single rooms, each with a bathroom but no kitchen. Jurvetson stayed in room 306 on a floor that had 17 other suites.

The apartment building was originally called the Paramount Hotel and in the 1940s had businesses on the main floor including a Tires and Tubes storeand a restaurant called Rosalin that offered steaks and beer.

On one side of the building was a parking lot. On the other side was a company called the Western Costume Co. store.

By the 1960s, according to the Los Angeles Department of Building Safety, the hotel had been converted into an apartment building. By the time Jurvetson arrived in October 1969, it was owned by a woman named Joy Szerlip.

In the absence of any other clues, M. Lindhorst presents a tantalizing possibility. Could he or she reveal what Jean's surname was? Or provide a timeline of when exactly Jurvetson was last seen in the building?

the fifth estate has also been pursuing another potential lead. Asketch of Jean, based on the memory of witnesses, has been circulated by the program since August. To date, no one has been able to find him or confirm his identity.

Witnesses told the fifth estatethat in the 1960s, Jean had a slim build, was more than five feet nine inches tall and had brown eyes that were shaped a bit like musician John Lennon's. They said he had long, fine, brown hair feathered back in the Rick Springfield style that was popular at the time.

He was originally from Montreal and had a slight French accent.

Without a surname, one lead to pursue is tracking down anyone named Jean who graduated from a Montreal high school between 1964 and 1968.

And so the fifth estate is asking anyone who attended one of the following 10 high schools to scan theirgraduating class photos from their yearbook. The images can be sent to janedoe59@cbc.ca.

• College Prep International.
• Montreal High School (known today as F.A.C.E. School).
• Herzilah High School.
• James Lyng High School.
• Laurier Macdonald High School.
• Lester B. Pearson High School.
• Rosemont High School.
• Montreal West High School (known today as Royal West Academy).
• St. George's School of Montreal.
• Vincent Massey Collegiate.

Jurvetson's case saw a major breakthrough in June 2015, when one of her friends called the LAPD to say she recognized the 19-year-old's morgue photo online. Jurvetson was positively identified through DNA testing.

Jurvetson's body had been found without any identification in 1969 and her family never reported her missing.

An undated note written by Jurvetson's mother, Silvia, suggests that although she never reported her daughter missing, she did not give up looking for her.

The note, which was found among her possessions, reads: "REET JURVETSON or who know of her whereabouts please call (collect) her widowed mother in Westmount Canada." The note included a phone number.

Silvia Jurvetson died on April 28, 2000. According to her surviving family, she wasstill tormented about what may have happened to her youngest child.

the fifth estate is actively searching for clues and is inviting the public to take part in itsinvestigation by joining the Facebook page for the story, Facebook.com/JaneDoe59, and submitting any clues.

You can also emailthe fifth estatedirectly at janedoe59@cbc.ca.

You can view the fifth estate's Instagram series at Instagram.com/ronna_syedor twitter.com/Ronna_Syed.

The final instalment of the story will be broadcast in a documentary titled "Who killed Jane Doe 59?" that will air on the fifth estate on CBC-TV on Nov. 18 at 9 p.m.