Miranda Grubbs, Associated Press
FILE - In this April 9, 2014 file photo, Alice Uden listens to the judge during jury selection in her murder trial at the Laramie County District Court in Cheyenne, Wyo. On Monday, Aug. 25, 2014, a judge in Cheyenne is scheduled to sentence Alice Uden, who killed her husband with a bullet to the head in the mid-1970s. The 75-year-old faces at least 20 years in prison but could get up to a life sentence.

CHEYENNE, Wyo. — A judge on Monday is scheduled to sentence an elderly Missouri woman to between 20 years and life in prison for fatally shooting her husband in the head in Wyoming in the mid-1970s.

Last fall, authorities arrested Alice Uden, 75, and Gerald Uden, 72, of Chadwick, Missouri, in southwest Missouri in separate murder cases dating back more than 30 years. Prosecutors haven't linked the two cases.

In May, jurors in Cheyenne found Alice Uden guilty of second-degree murder. Her attorneys argued unsuccessfully she had to kill Ronald Holtz, 25, to defend her toddler daughter from him.

The claim that Holtz, her third husband, was abusive could come up again at sentencing before Laramie County District Court Judge Steven Sharpe in Cheyenne.

The shooting happened at the couple's home in Cheyenne in late 1974 or early 1975. Uden testified she shot Holtz with a rifle next to the girl's bed.

Uden said she put Holtz's body in a cardboard barrel, wrestled the barrel into her trunk and dumped the barrel in an abandoned gold mine on a ranch between Cheyenne and Laramie.

Prosecutors argued Uden shot Holtz with a rifle as he slept. One of Uden's sons, Todd Scott, testified his mother told him decades ago she'd shot Holtz while he was asleep.

After several previous attempts to find Holtz's remains in the mine filled with the carcasses of cattle and other ranch animals, investigators last summer dug deeper in the vertical shaft than ever before and finally excavated Holtz's remains.

The jury declined to find Uden guilty of premeditated, first-degree murder, which would have carried a mandatory life sentence. The jury also declined to convict her of the least-serious charge, manslaughter.

Already serving life in prison is Uden's fourth and current husband, Gerald Uden, 72, who pleaded guilty in November to three counts of first-degree murder for shooting his ex-wife and her two children in central Wyoming in 1980.

Authorities arrested the couple in southwest Missouri last fall. Prosecutors haven't drawn any link between the two cases.

The bodies of 32-year-old Virginia Uden, and her two sons, 11-year-old Richard Uden and 10-year-old Reagan Uden, have yet to be found. Gerald Uden told a Fremont County courtroom in November he shot each of them with a rifle not far from his home, one after the other, and dumped their bodies in an abandoned mine.

Months later, he said, he retrieved the bodies and sank them in Fremont Lake in western Wyoming. Investigators briefly searched the lake for the bodies last fall.