Mathison, convicted in November, was sentenced to life plus 20 years in prison with the possibility of parole.
Today, state Attorney General Margery Bronster said the authority has given Mathison, 45, a minimum of 25 years for the murder charge and 20 years for the kidnapping, meaning he will not be eligible for parole until Nov. 8, 2020, just before his 70th birthday.
Bronster said the decision sends a clear message that domestic violence cases will be investigated and prosecuted to the full extent of the law no matter who commits the crime.
"Even though Mathison was a police sergeant who used his knowledge as a police officer to attempt to cover up his crime, and even though the case was complex and costly to prosecute, the prosecution relentlessly pursued the case until Mathison was convicted," Bronster said.
The group Citizens for Justice alleged a police cover-up in the case, which took three years to go to trial.
Yvonne Mathison died Nov. 27, 1992, after she was beaten with a pipe and run over by a van. Prosecutors said Mathison killed her because he wanted to collect half a million dollars in insurance.
Deputy Attorney General Kurt Spohn, who prosecuted the case, today called the minimum sentence tough but appropriate.