The death of 47-year-old Russell Armstrong was caused by hanging and no note has been found, Los Angeles County Assistant Chief Coroner Ed Winter said.
Armstrong, who was married to "Housewives" Taylor Armstrong, was pronounced dead at 8:16 p.m. Monday in a home on Mulholland Drive, Winter said.
Bravo, home of the "Real Housewives" reality franchise, said in a statement Tuesday that "all of us at Bravo are deeply saddened by this tragic news. Our sympathy and thoughts are with the Armstrong family at this difficult time."
Russell Armstrong was an investment banker and venture capitalist. His relationship with his wife was a big part of the drama on the first season of "The Real Housewives of Beverly Hills," which peeks into the privileged lives of six women living in the posh neighborhood.
Armstrong appeared on many episodes, accompanying wife Taylor to events. She often discussed the couple's relationship troubles with the other women on the show, which premiered last fall.
In February, she wrote on her website that she and her husband "are working on our communication and spending more time together. without our Blackberrys" and that "the show gave us a wakeup call and for that, we are thankful."
The second season is set to begin Sept. 5. In the opening episode, filmed months ago, Taylor Armstrong tells the other housewives that she and her husband are going to therapy.
Later, she bursts into tears at a dinner party when one of the other women's husbands tells her that therapy is a sign of weakness. She is also shown shopping for lingerie to help spice up her marriage.
Bravo provided an advance copy of the premiere episode to the press last week.
Court records show Taylor Armstrong filed for divorce on July 15 in Los Angeles. Russell Armstrong had not yet responded to her petition.
The couple was sued last month for $1.5 million by a company that claims the pair diverted money from investors to promote their lavish lifestyle, including redecorating their mansion.
The complaint stated Russell Armstrong represented himself to be a successful venture capitalist who claimed he had procured $2 billion for various entities.
His publicist, Rebekah Iliff, said he was the founding managing director of Crescent Financial Partners. She confirmed the couple was in the midst of a divorce.
The couple's relationship troubles were set to be part of the show's second season, said fellow housewives Kyle Richards and Camille Grammer, whose own divorce from ex-husband Kelsey Grammer played out on the first season of show.
Richards said in an interview last week that viewers could expect to see "Taylor's situation, just seeing that unravel and it's a very emotional subject; a very difficult subject."
Richards and Grammer said they weren't surprised that Taylor Armstrong filed for divorce.
"I think we all saw in season one that they weren't exactly a match made in heaven," Richards said.
Taylor Armstrong often complained to her cast mates that she felt neglected by her husband. She says on her website that she met him in 2004, and court records show they were married in 2005.
They have one daughter, 5-year-old Kennedy Caroline Armstrong.
Besides Taylor Armstrong, Richards and Grammer, "The Real Housewives of Beverly Hills" stars Adrienne Maloof, Kim Richards and Lisa Vanderpump. Two other women joined the show in its second season: Dana Wilkey and Brandi Glanville, who is dealing with the aftermath of her own high-profile divorce.
Glanville's ex-husband, actor Eddie Cibrian, recently married singer Leann Rimes after an apparent affair documented in tabloids and online.
"The Real Housewives of Beverly Hills" is the newest in the "Real Housewives" franchise, which follows affluent women in cities such as Atlanta, Miami and New York City.
Some of the other "Housewives" took to Twitter and Facebook to express their condolences.
"Shocked and deeply saddened to hear about the passing of Russell Armstrong," Jill Zarin, who appears on the New York City version, tweeted Tuesday.
"No words can express how much my heart is breaking for my fellow housewife sister (at)taylorarmstrong and her daughter," Gretchen Rossi, who appears on "The Real Housewives of Orange County," wrote on Facebook. "Please keep her and her family in your prayers and thoughts today. RIP Russell Armstrong."
AP Entertainment Writers Anthony McCartney and Derrik J. Lang in Los Angeles, and Lauri Neff in New York contributed to this report.