In the last, driver Conrad Johnson, 35, was shot as he prepared to begin his Ride On bus route near the Aspen Hill section of Silver Spring. Malvo's admission that he was the shooter squares with some of the forensic evidence, which authorities say puts Malvo's DNA on items in the woods from which police believe the fatal shot came.
Whatever Malvo's reaction to Muhammad is in the courtroom, it cannot harm the prosecution, said a person who knows Malvo but did not want to be identified because of Muhammad's continuing trial. Malvo can provide detail about crimes, which would benefit the prosecution. If he withers on the witness stand, Muhammad's hold over him will be obvious to a jury, the person said.
Legal experts note that it is possible to obtain a conviction against Muhammad without Malvo - it was done in Virginia - because, they say, the circumstantial case against the Persian Gulf War veteran is solid and overwhelming. But Malvo's first-person account can wrap together what jurors have heard in testimony by forensic experts and others, legal experts say.
For example, Walter Dandridge, a federal firearms examiner, conclusively tied the .223-caliber Bushmaster rifle found in the Caprice to four of the six killings in Montgomery County, and a total of 12 of the 14 sniper shootings presented to jurors.
David McGill, a Montgomery County police evidence collector, linked the rifle to Muhammad's car. And FBI analyst Brendan Shea testified that Muhammad's DNA was on the sight for that rifle - and perhaps on the rifle itself, along with Malvo's.
Though prosecutors can pull them together in closing arguments, Malvo can connect the dots sooner, giving jurors reference points to think about while the defense presents its case.
"He is going to make some critical links in the evidence," said Christopher L. Tritico, who served as a defense lawyer for Oklahoma City bomber Timothy J. McVeigh.
Though Muhammad obtains advice from any of three standby lawyers, he is neither a skilled nor detached questioner. That raises the possibility that the way Muhammad frames questions to Malvo will backfire on Muhammad, Tritico said.
"He can say, 'Isn't it true I told you this?' and implicate himself," Tritico said.
Even the inconsistencies in Malvo's statements - and highlighting inconsistencies is a hallmark of cross-examination - are unlikely to undermine the prosecution's case, predicted Robert F. Horan Jr., the Fairfax County commonwealth's attorney who obtained a life sentence without parole for Malvo.
"For prosecutors there is no downside," he said. "Muhammad is not a lawyer. He just doesn't know so many different things about cross-examining people."
Sources close to the case say Malvo will plead guilty, which will add multiple life-without-parole sentences in Maryland to his Virginia life-without-parole sentences for three sniper shootings there, two of them fatal.
But Horan, saying Malvo would not do something for nothing, speculated that he might be angling for something as seemingly minor as better prison accommodations.
Paul B. Ebert, who prosecuted Muhammad for capital murder in Prince William County, Va., added of Malvo: "It would be interesting to see what he's got to say."