Jurors late Friday began deliberating whether fallen Silicon Valley star Elizabeth Holmes conned investors or earnestly believed the technology used by her blood-testing startup could revolutionize the industry.

After more than three months of testimony, during which Holmes testified in her own defense, the panel of four women and eight men was sent to mull whether she is guilty of fraud charges that could send her to prison for years.

Jurors went home in the evening and will resume deliberations next week.

During closing arguments, prosecutors accused Holmes of choosing "fraud over failure," lying to investors and patients as her technology fizzled and cash ran low.

Holmes's lawyer Kevin Downey countered that Holmes truly believed in her invention, and was on the cusp of realizing her dream -- of doing a wide range of blood tests with just a few drops of blood -- when the startup sank.

Elizabeth Holmes (L), founder and former CEO of blood testing and life sciences company Theranos, leaves the courthouse with her husband Billy Evans after the first day of her fraud trial in San Jose, California
Elizabeth Holmes (L), founder and former CEO of blood testing and life sciences company Theranos, leaves the courthouse with her husband Billy Evans after the first day of her fraud trial in San Jose, California AFP / Nick Otto

"First sign of trouble, crooks cash out, criminals cover up and rats flee a sinking ship," Downey told jurors, pointing out that Holmes worked until the end to salvage the startup and never sold any shares in the company.

"She went down with that ship when it went down," Downey said.

Holmes potentially faces years in prison if convicted on allegations she defrauded investors and clients of her once-hyped firm Theranos, which collapsed after it was revealed the machines did not work as promised.

The high-profile case has drawn intense media attention and posed questions about how far startups can bend the truth.

Holmes launched Theranos in 2003 at age 19, eventually promising self-service testing machines that could run an analytical gamut cheaply and on just a few drops of blood -- a pledge shattered under fraud allegations.

In many ways, Holmes fit the stereotypical image of a Silicon Valley entrepreneur, from her dark-colored turtleneck sweaters that evoked tech legend Steve Jobs to her dropping out of California's elite Stanford University.