43-year-old Ana Maria Gonzalez-Angulo, a breast cancer doctor in Texas had been involved in a relationship with her fellow researcher George Blumenschein at the University of Texas MD Anderson Cancer Center.
Prosecutors said the affair turned into a "fatal attraction" and she poisoned him with ethylene glycol in 2013 after Blumenschein spurned her in favor of Evette Toney, his live-in girlfriend of 10 years with whom he was trying to start a family.
Defence attorneys had argued for probation, saying a prison term would be a waste given Gonzalez-Angulo's work.
"She could still be a researcher, looking for ways to cure breast cancer," attorney Derek Hollingsworth told jurors, according to the Houston Chronicle. "Or she could sit in a jail cell, be a ward of the state."
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Jurors deliberated for about four hours over two days before reaching their verdict. Gonzalez-Angulo had no visible reaction after the verdict was read.
Witnesses testified that Gonzalez-Angulo had access to ethylene glycol at the University of Texas MD Anderson Cancer Center where she and Blumenschein worked.
Gonzalez-Angulo's attorneys argued that other people, including Toney, might have been responsible for the poisoning, an allegation that Toney has denied.
The defence team also noted a prosecution expert's testimony that Blumenschein could have ingested the poison two days earlier.
The trial, which began on September 15, was filled with plot twists straight out of a soap opera, including prosecutors' claims that Gonzalez-Angulo lied about being attacked outside her home in an effort to get Blumenschein to leave his girlfriend. Prosecutors also said Blumenschein secretly recorded calls in which he tried to get Gonzalez-Angulo to confess to poisoning him.
The trial's punishment phase began after the verdict was read and concluded later Friday after both sides presented witnesses.
Assistant Harris County District Attorney Justin Keiter commended the jury for its decision, noting that it probably wasn't easy to send a doctor who works to cure cancer to prison.