(CNN) -- Utah doctor Martin MacNeill was found guilty of his wife's murder in a verdict read early Saturday morning.
MacNeill showed no emotion as he learned his fate, but a yell came from the section where his relatives sat.
He will be sentenced later on the charges of first-degree murder and obstruction of justice.
MacNeill had said his wife's death was an accident.
In the end, jurors believed prosecutors' allegations that MacNeill drugged and then drowned his wife, Michele MacNeill, in the bathtub of their home on April 11, 2007, to be with his mistress.
MacNeill, who had been on trial for 22 days in Provo, Utah, had pleaded not guilty to charges of murder and obstruction of justice.
Prosecutors alleged that his actions after his wife's death hindered the investigation, forming the basis for the obstruction of justice charge.
However, defense attorneys said his wife, who was found with a powerful cocktail of prescription drugs in her system, died of natural causes.
None of the medical examiners who worked on the case could determine definitively whether she died as a result of homicide.
One of MacNeill's daughters, Alexis Somers, said she was happy with the verdict.
"There was justice for my mom today," Somers said. "We are just so happy he cannot hurt anyone else."
During his closing arguments Friday morning, prosecutor Chad Grunander pleaded with jurors to return a guilty verdict on both counts.
"Martin MacNeill murdered his wife, Michele. Her death was not the result of an accident, and it certainly was not the result of a heart condition," Grunander said. "The defendant carried out a cold and calculated plan to murder his wife. He relied on his knowledge and experience as a doctor and also as a lawyer to accomplish this."
In his closing argument, defense attorney Randall Spencer said prosecutors had simply not proved their case.
"There's not evidence in this case that rises to the level of guilt beyond a reasonable doubt," Spencer said. "The prosecution has presented to you their cherry-picked versions of the evidence that is most consistent with their theories."
Prosecutors also called Gypsy Willis, Martin MacNeill's former mistress, to the witness stand. She admitted having an affair with Martin MacNeill both before and after Michele MacNeill's death.
Less than two weeks after his wife died, MacNeill hired Willis as the family nanny to take care of his four youngest children.
MacNeill could spend the rest of his life in prison for his convictions. He faces 15 years to life in prison for murder, and he could be sentenced to up to 15 years for obstruction of justice.
The MacNeills had eight children, and to many in their community, they seemed to be living an idyllic life in a gated community when Michele MacNeill died. More than one of the children, however, has since come forward and accused their father of killing their mother.
Rachel MacNeill, their oldest biological daughter, attended Friday's proceedings and cried as the judge read jury instructions before closing arguments even began. She cried as the verdict was read.
HLN's Graham Winch contributed to this report.
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