Wagner is charged in the deaths of Daniel Davis, 84, and his wife, Wilda Davis, 80, who were each stabbed multiple times in their 109 W. Wilson Blvd. home on Feb. 14, 1994, and left to die, Michael said.
Their bodies were found on Feb. 15.
The jury of five women and seven men is considering whether to find Wagner, 50, not guilty, guilty of two counts of first-degree murder, or guilty of two counts of felony murder and one count of burglary. A felony murder charge is applicable when a murder takes place while a felony, such as a burglary, is being committed.
If the jury decides Wagner is not guilty of first-degree murder or felony murder, the jurors may consider the lesser charge of second-degree murder, Washington County Circuit Judge Frederick Wright said.
Wagner was tried on first-degree murder charges in the couple's deaths in 1996. A Garrett County, Md., jury was unable to reach a verdict. He was re-indicted in 2001.
In his rebuttal argument, Michael said he was confident the jurors would use common sense and disregard a scenario presented by the defense during closing arguments.
Both Michael and Harris suggested to the jury that Ted Monger, the son-in-law of Daniel and Wilda Davis, was involved in their deaths, but their scenarios differed.
On Tuesday, Harris suggested to the jury that the Davises were not killed on Feb. 14 but during the early hours of Feb. 15 by Ted Monger, the couple's son-in-law.
Harris said that if the Davises were killed on the morning of Feb. 15, Wagner could not have been involved because he was working for a Frederick County contractor.
Harris suggested to the jury that Monger went to the home under the guise of picking up a container of potato salad and stabbed the couple to death so that his wife, Vivian Monger, would inherit $50,000.
A felon and laborer, Wagner made the perfect "fall guy," Harris told the jury.
Wagner was occasionally employed by Monger and lived in his Chestnut Street apartment building in 1994.
Monger was never charged in connection with the deaths of the Davises.
More than one person likely committed the crime and police are still working on the case, Michael said.
"Russell Wagner is the first domino to fall," Michael told the jury.
Wagner told three people that he was inside the Davis home ransacking it while the couple was being killed, Michael said.
Michael suggested that Wagner and possibly another man waited outside the Davis home on Feb. 14, 1994, while Ted Monger knocked on the door. Wilda Davis was expecting Monger to stop in to pick up potato salad she had made for her daughter, Michael said.
Monger left the door open and feigned fear as Wagner and the other man rushed in and threatened them with a knife, Michael said. One of the men retrieved pillow cases and put one on each of the Davises. Michael said Monger might have told them they would be OK if they didn't fight.
A third pillowcase found on the floor in the Davis home was likely intended to be placed on Monger's head so the Davises wouldn't suspect he was involved, Michael suggested to the jurors.
As Michael presented his theory, Vernon Davis, the son of Daniel and Wilda Davis, began to shake. After a few minutes, he rushed from the room, followed by several family members who began to cry.
Wagner, who showed no emotion throughout the seven-day trial, shook his head and mouthed the word "no" at one point during Michael's rebuttal argument.
Michael contended that Wagner was not merely an observer of the crimes because a DNA expert with the FBI testified that a hair that might have come from Wagner was found on a glove with Daniel Davis' blood on it.
The Davises could not have been killed on Feb. 15, 1994, as Harris suggested in his closing argument, because they were fully dressed, lights were on throughout the home and a bath had been drawn, Michael said.
A family member testified that the Davises bathed at night.
Wagner has no alibi for the time of the murders and was overheard discussing a plan to murder the couple with the late Charles Harmon, Monger's business partner, Michael said.