Yang was convicted in March of shooting and killing Reuter, 42, and her unborn child in 2007. Gayle had relationships with both women.
"This is just the worst as far as planning, perpetration, ability to deliberate, ability to choose that I've ever seen in my career as a prosecutor," said Patricia Fix, Lake County assistant state's attorney.
Reuter's brother made an impact statement in tears.
"Instead of planning on welcoming a new life, we were planning a double funeral," said Thad Reuther. "Not a day goes by that we don't think of Rhoni...it's just not fair that we will never get to see her again this side of heaven." Referring to Yang, he said, "An individual who should never have the remote possibility of seeing one day of freedom."
Gayle, who was not in court, withdrew his impact statement after hearing defense attorneys planned to challenge whether he was the father of the Reuter's unborn child. His attorney, Donna Rotunno, read that statement: "My biggest mistake was meeting you, Marni Yang, and letting you into my life. When you stood in the doorway and executed her and killed our daughter, you took my life too."
Defense attorneys had asked for a minimum sentence of 45 years, but the judge cited the months of preparation and attention to detailed planning of the murder that warrants life in prison.
"Any sentence that would be imposed would have the same effect. Her reaction is essentially the same. It's not something you accept easily," said Jeffrey Lerner, defense attorney.
Yang was asked if she wanted to make comment in court. She said she was too nervous and asked her attorney to read her statement which said, "I would like to express my sorrow for the family. I am truly sorry for their loss."
Investigators have released interrogation video of Yang and surveillance video of her buying supplies to make a silencer. In court Friday, Yang's attorneys argued that they were not allowed to present evidence or perform proper cross-examination during the trial. Yang's attorneys also argued that she did not get a fair trial because she was never allowed to put on makeup or get a new hairstyle. At one point one of her attorneys also said that she looked haggard. They asked for a new trial. That motion was denied.
During the trial, prosecutors said Yang hacked into Gayle's e-mail account and discovered Gayle's relationship with Reuter and found out about the baby.
Yang gunned Reuter down as Yang wore a disguise and hid evidence. Prosecutors used a wiretap on Yang's friend to prove the case. Gayle said after the verdict he also had to ask Yang undercover questions.
"This has been very difficult for me and for Rhoni's family," he said. "At least I feel that they are at peace. I had to sit and have conversations with Marni Yang while law enforcement was sending text messages throughout the conversation of questions to ask. Of course, there were times when things got -- it was crushing."