Former University of Pittsburgh researcher Robert Ferrante has been found guilty of murdering his wife, Autumn Klein, by lacing her energy drink with cyanide.

Prosecutors said neuroscientist Robert Ferrante concocted the plan to kill Autumn Klein after she pressured him to have a second child.

Robert Ferrante now faces a mandatory life sentence.

Autumn Klein’s relatives burst into tears upon hearing the guilty verdict in the Pittsburgh court.

“Justice for Autumn,” said her mother, Lois Klein, outside the court.

The jury deliberated for 15 hours over two days before finding Robert Ferrante, 66, guilty of first-degree murder.

Former University of Pittsburgh researcher Robert Ferrante has been found guilty of murdering his wife, Autumn Klein, by lacing her energy drink with cyanide

Robert Ferrante hung his head when the verdict was read out.

Police said Robert Ferrante had given the supplement to his wife on April 17 2013. She died three days later.

Prosecutors described him as a “master manipulator” and said he may also have acted out of fear that she was having an affair or was planning to divorce him.

Robert Ferrante had denied poisoning Autumn Klein, saying he had bought the cyanide for stem cell experiments.

Police said Robert Ferrante used a university credit card two days before Autumn Klein fell ill to buy more than 8oz of cyanide.

His lawyers made the case that Autumn Klein, 41, might not have been poisoned at all, citing three defense experts who said poisoning couldn’t be conclusively proved.

The prosecution, however, maintained that a test on Autumn Klein’s blood had revealed a lethal level of cyanide.

The blood was drawn while doctors tried for three days to save Autumn Klein’s life, although the results were not known until after she had died and her body was cremated.

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