As a prison bus rumbled through the darkness on a winter night, passing through four Maryland counties and into Baltimore on a 75-mile trek to the city's Supermax prison, Parker was strangled and left slumped between rows of seats.
"Baltimore County seeks the death penalty much, much, much more frequently than any other venue, so certainly on the defense side, you don't want to be in Baltimore County," said Byron L. Warnken, a University of Baltimore law professor.
The death penalty is never mentioned in court papers challenging Baltimore County prosecutors' right to try Johns, 22, but it lurks under the surface.
In 2002, researchers from Columbia, Rutgers and New York universities ranked Baltimore County second among large counties nationwide in the rate at which convicted murderers are sentenced to death. A University of Maryland study released a year later found that the county dominates the state in death-penalty cases and that prosecutors there are 13 times more likely to seek the death penalty than are prosecutors in the city.
"The stakes are very high for Mr. Johns," said Douglas Colbert, a University of Maryland law professor.
A hearing to determine which jurisdiction should try the case was originally scheduled for last month but was delayed because of the illness of one of Johns' lawyers. Last week, Baltimore County Circuit Judge Thomas J. Bollinger postponed the matter until the first week of January and set a trial date for July 31.
While Johns' case might seem an apt one for any prosecutor to consider seeking the death penalty - he has previously been convicted of two murders, one inside and one outside prison - the decision for many jurisdictions often comes down to a question of resources, court observers say.
In other areas, "there are so many factors that enter that decision," Colbert said.
William C. Brennan Jr., one of Johns' lawyers, would not comment beyond the court filings in the case.
Evidence conflictsExactly what led authorities to choose Baltimore County as the place to charge Johns is unclear. Prosecutor S. Ann Brobst said there is "ample evidence" that Parker was killed in Baltimore County, but she would not discuss the specifics.
A termination notice for one of the correctional officers involved in the transport notes that "the trip proceeded without apparent incident" until the bus reached the area of Security Square Mall in the county, where one officer said he saw Johns switch seats "and became suspicious that there was a problem."
Johns and Parker, 20, were among more than 30 inmates and five correctional officers on the bus as it traveled along Interstate 70 from the Maryland Correctional Training Center near Hagerstown to the Maryland Correctional Adjustment Center, also known as Supermax, during the early-morning hours of Feb. 2.
Johns' lawyers argue in court filings that the strangling likely took place in Howard County - although they also point to statements from inmates on the bus that alternately place the act in Washington, Frederick and Howard counties.
Johns said in an interview with authorities that the attack took place about 15 minutes after the bus left the Hagerstown prison, according to a defense brief.
Evidence points to the attack taking place before the bus reached Baltimore County, making that jurisdiction the wrong venue for the case, the lawyers wrote.
Case is 'trickier'