Francis was found guilty by Judge Edward Rubin after a two-day bench trial.
He murdered Linda Bonin on April 1, 2009 during a home invasion-burglary gone awry, after first violating her anally with a sex toy found in the house.
Two co-defendants - Ryan Williams and Claude Morrison, Jr., both 15 at the time of the crime, plea bargained earlier in exchange for their testimony.
Williams, who got 12 years on reduced charges, proved to be a hostile, uncooperative witness for the both the prosecution and defense on Tuesday.
Morrison, who has pleaded guilty to reduced charges but not been sentenced pending his testimony, invoked the 5th Amendment against self-incrimination even though he has already pleaded.
A third man, Ove Wilson, charged with Francis in a separate murder, also invoked the 5th when called by the defense. His trial is scheduled in January.
On Monday, Ryan Snow, in the house when the three barged in, testified Francis killed Bonin when she would not stop screaming.
Williams said the same on Tuesday.
Snow was shot in the arm during the robbery attempt and played dead, he said, while the bandits tore apart the house and Bonin was assaulted, then shot.