FEB. 1, 2014, 10:00 PM, ET/PT

Captions: (L-R) Sylvie Cachay; Nicholas Brooks

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Troy Roberts and 48 HOURS go inside the investigation into the death of critically acclaimed swimsuit designer Sylvie Cachay and her ties to the son of an Oscar-winning songwriter in “Death at Soho House” to be broadcast Saturday, Feb. 1, 2014 (10:00 PM, ET/PT) on the CBS Television Network.

It’s a case that ties the worlds of high fashion and entertainment, and exposes deep family secrets about the songwriter behind the 1970s hit, “You Light Up My Life.”

Sylvie Cachay was a rising swimsuit designer who had worked with the likes of Marc Jacobs and Victoria’s Secret before launching her own line, Syla.

But in 2010, she was found by a Soho House worker, dead and partially clothed in an overflowing bathtub.

“Sylvie went into the Soho House looking beautiful and alive, then she came out in a body bag,” says Susan Karten, an attorney representing Cachay’s family.

Police noticed an empty bottle of prescription pills nearby, which raised the question of whether she killed herself or if it was an accident.  However, the medical investigator on the scene spotted marks on her neck, suggesting she was strangled. Police also learned Cachay had checked into the hotel earlier with her boyfriend, Nicholas Brooks, the son of Academy Award-winning songwriter Joseph Brooks.

The investigation quickly turned to Brooks.

“My brother absolutely did not murder Sylvie Cachay,” Amanda Brooks tells 48 HOURS.  

Amanda Brooks discusses their childhood and how the family was torn apart when her parents divorced. She also maintains that her father’s famous name made her brother’s connection with Cachay a “whirlwind of a story.”

Amanda says Nick told her the bruises on Cachay’s neck were because of rough sex. “I know my brother’s innocent,” she adds. “I mean this obviously was a grave mistake.”

Manhattan District Attorney Cy Vance disagrees. “The bruising around her neck was clear evidence of strangulation,” Vance tells 48 HOURS. “The fact that her lungs had twice their ordinary weight indicated that she was put into the tub alive and breathing.”

Was Cachay’s death an accident or murder? Roberts and 48 HOURS piece the story together through interviews with Cachay’s family and friends, Brooks’ sister and attorney, police who worked on the case, and journalist and 48 HOURS consultant Murray Weiss. 48 HOURS: “Death at Soho House” is produced by Patti Aronofsky and Elena DiFiore. David Spungen is the producer-editor. Al Briganti is the executive editor. Susan Zirinsky is the senior executive producer.

Chat with members of the 48 HOURS team during the broadcast on Twitter and Facebook.

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Press Contact:  Richard Huff      212-975-3328    huffr@cbsnews.com