SAN FRANCISCO — Theranos Inc. has begun drawing on a wider network of law firms, amid a rift with its once-stalwart ally Boies, Schiller & Flexner.

The embattled Silicon Valley company has been besieged by lawsuits from customers, investors and business partners following reports of its failure to deliver on its promised blood-testing technology.

On Tuesday attorneys at Wilmer Cutler Pickering Hale and Dorr entered appearances for Theranos in a proposed class action in San Francisco federal court on behalf of investors who say they were duped into buying shares in the private company.

The attorney identified as lead counsel for Theranos in the case is Michael Mugmon, a Wilmer Cutler partner in Palo Alto. He declined to comment, but according to his firm bio, Mugmon’s practice “focuses broadly on crisis management for companies and individuals facing significant regulatory actions and litigation.”

It’s the second lawsuit against Theranos in which Wilmer has publicly entered an appearance. The firm is also representing Theranos in a suit brought by a hedge fund in Delaware, and The Wall Street Journal reported last month that Wilmer had started handling government investigations into the company after Theranos split with Boies Schiller over strategy.

Another firm that Theranos has turned to is Cooley. Firm chairman Stephen Neal and Kathleen Goodhart, head of Cooley’s Bay Area litigation practice, are representing Theranos CEO Elizabeth Holmes in the investor suit in Delaware. Cooley also stepped in on Holmes’ behalf earlier this month in a consumer class action pending in Arizona federal court after Boies Schiller attorneys withdrew.

According to Theranos’ website, Boies Schiller founding partner David Boies continues to sit on the company’s board of directors. The firm had represented Theranos for years, including in a patent feud against a father-son inventor team that predated its current woes.

Edward Evans, a spokesman for Boies Schiller, deferred an inquiry about the firm’s split with Theranos to the company. Theranos did not respond to a request for comment.

Meanwhile, in a lawsuit brought by Theranos’ former business partner Walgreens last month in the U.S. District Court of Delaware, Theranos is now being represented by Wilkinson Walsh + Eskovitz. The small trial firm was founded earlier this year by a group of litigators from firms such as Paul, Weiss, Rifkind, Wharton & Garrison and Munger, Tolles & Olson.

Contact Ben Hancock at bhancock@alm.com. On Twitter: @benghancock.

SAN FRANCISCO — Theranos Inc. has begun drawing on a wider network of law firms, amid a rift with its once-stalwart ally Boies, Schiller & Flexner .

The embattled Silicon Valley company has been besieged by lawsuits from customers, investors and business partners following reports of its failure to deliver on its promised blood-testing technology.

On Tuesday attorneys at Wilmer Cutler Pickering Hale and Dorr entered appearances for Theranos in a proposed class action in San Francisco federal court on behalf of investors who say they were duped into buying shares in the private company.

The attorney identified as lead counsel for Theranos in the case is Michael Mugmon, a Wilmer Cutler partner in Palo Alto. He declined to comment, but according to his firm bio, Mugmon’s practice “focuses broadly on crisis management for companies and individuals facing significant regulatory actions and litigation.”

It’s the second lawsuit against Theranos in which Wilmer has publicly entered an appearance. The firm is also representing Theranos in a suit brought by a hedge fund in Delaware, and The Wall Street Journal reported last month that Wilmer had started handling government investigations into the company after Theranos split with Boies Schiller over strategy.

Another firm that Theranos has turned to is Cooley . Firm chairman Stephen Neal and Kathleen Goodhart, head of Cooley ‘s Bay Area litigation practice, are representing Theranos CEO Elizabeth Holmes in the investor suit in Delaware. Cooley also stepped in on Holmes’ behalf earlier this month in a consumer class action pending in Arizona federal court after Boies Schiller attorneys withdrew.

According to Theranos’ website, Boies Schiller founding partner David Boies continues to sit on the company’s board of directors. The firm had represented Theranos for years, including in a patent feud against a father-son inventor team that predated its current woes.

Edward Evans, a spokesman for Boies Schiller , deferred an inquiry about the firm’s split with Theranos to the company. Theranos did not respond to a request for comment.

Meanwhile, in a lawsuit brought by Theranos’ former business partner Walgreens last month in the U.S. District Court of Delaware, Theranos is now being represented by Wilkinson Walsh + Eskovitz. The small trial firm was founded earlier this year by a group of litigators from firms such as Paul, Weiss, Rifkind, Wharton & Garrison and Munger, Tolles & Olson .

Contact Ben Hancock at bhancock@alm.com. On Twitter: @benghancock.