NATIONAL NEWS (CNN) — After six years of relentlessly pursing justice for Michele MacNeill, her daughter is thankful that justice has finally be served.
"Thanks to the prosecutors, the investigators, people who believed, believed us and fought for justice for my mother. She finally has justice," Alexis Somers, MacNeill's daughter, told HLN's Nancy Grace Monday night.
Early Saturday morning, a jury of eight found former Utah doctor Martin MacNeill, 57, guilty of first-degree murder and obstruction of justice in the death of his wife of nearly 30 years.
Prosecutors accused MacNeill of drugging then drowning his wife, Michele, in the bathtub of their family's home on April 11, 2007, so he could continue a relationship with his mistress, Gypsy Willis. The mother of eight was recovering from face-lift surgery at the time of her death.
Somers, who pushed investigators to re-examine the death of her mother, ultimately leading to her father's arrest, broke down in tears when the verdict was read early Saturday morning.
"It was just so surreal. This was a culmination of six years fighting to get justice for my mother. I was shaking, emotions just flooded out of me and I couldn't stop sobbing," she said. "It was so much relief. I felt like the weight of the world had been lifted off my shoulder."
Prosecutors first got the case against MacNeill during the investigation phase, and they admitted they face some significant challenges from the start.
"A lot of evidence was circumstantial," lead prosecutor Chad Grunander told Grace in an exclusive interview Monday night. "His actions are what really tell the story about who this man is."
"This was not a medical case, and medical science can't prove this can one way or the other," prosecutor Sam Pead said. "You have to look at all the other circumstances. We just had to demonstrated that all of these things ... they cannot be interpreted in any way outside of murder. It's that simple."
Jared Perkins, another prosecutor in the MacNeill case, discussed three questions in the case the jury could not ignore.
"Why did he lie about the position of Michele's body? Why did he destroy the pills? Why was he lying about the plastic surgery presenting to everyone after she died that it was her idea?" Perkins said. "There are certain things that, regardless of the medical evidence, could not be explained any other way than MacNeill's guilt."
Somers, who testified about some of those unexplainable circumstances at trial, told jurors how her mother confronted the former doctor about his affair before her death -- and how he admitted to overmedicating her mother the night she got home after having face-lift surgery.
"I was just trying to be honest and remember everything the best I could," Somers said. "I was looking at these people that were going to be deciding his fate, and I was just so concerned and hoping they would see my testimony for what it was and be able to convict my father. "
MacNeill's daughter told Grace she first suspected her father of murder moments after learning her mother was dead.
"I had just been told that my mother's in the bathtub and to come home. I dropped everything and I got in my car and I just started screaming, 'He killed her! He killed her," Somers said. "I just knew right away that he had done that. My mother had told me that if anything happens to her to make sure it wasn't my father. I knew it was him."
The jury never heard the damning statement Michele told her daughter just before her death. The judge banned that statement after MacNeill's defense argued it was hearsay, unreliable and would compromise MacNeill's right to a fair trial.
When asked what went through her mind when her mom made the statement, Somers told Grace she initially didn't believe her.
"I feel bad now that I didn't take it seriously at the time. But I just tried to downplay it and say, 'Mom, don't worry about that. That would never happen,' " Somers told Grace.
As for the defense's argument that Somers and her sisters hated MacNeill for disinheriting them from his will after their mother's death and framed him for murder, Somers told Grace their theory didn't make sense.
"I loved my father. I loved him for so many years. I would protect him, and I would have died for him," she said. "I was never in this for any other reason but to get justice for my mother."
However, the father she once loved refused to lock eyes with her inside the courtroom, Somers said.
"He was very cold. I don't think he expressed any emotion, but he definitely did not ever look at me," she said.
Six years after her mother's death, MacNeill's daughter said it's hard to believe this nightmarish chapter in her life is coming to a close.
"I can't believe it. I wake up every morning for the last two days and have to remind myself that it's really over," Somers said. "I'm just so grateful this is over and justice is served. Now I can move on, and my mother would want us to move on and focus on the good things we have to come."
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.
Judge Derek Pullan scheduled MacNeill's sentencing for January 7.