Every morning, a black sedan picks up the chief of naval operations at his home and drives him to his office at the Pentagon. Waiting for him inside the sedan is a briefing book with highly classified materials provided by administrative assistants who arrive at the Pentagon as early as 4 a.m. One day last December, Chief of Naval Operations Gary Roughead entered his black sedan to find that the classified briefing was missing. That set into place a series of telephone calls to find out what happened to Juantissa Hill, a 24-year-old second-class petty officer who was responsible for preparing the classified materials that morning.

"She was always on time, very punctual," said Senior Chief Petty Officer John Perez, Hill’s supervisor at the Pentagon. "She was never late or tardy."

In testimony at the Alexandria courthouse this week, Perez testified that he called Walter Reed Army Medical Center, Inova Alexandria Hospital and the Virginia State Police before asking an employee to stop by her apartment to check on her. The office at EOS 21 apartments was reluctant to let a stranger into Hill’s apartment, so Perez called the police. Officers responded within minutes, entering the apartment to check on Hill’s welfare. Inside, officers found Hill’s lifeless body — strangled to death in a chaotic crime scene.

"The apartment appeared to be in a state of disarray," said Commonwealth’s Attorney S. Randolph Sengel during his opening statement Monday morning. "The bedroom appeared to be ransacked."

DURING A THREE-DAY murder trial this week at the city courthouse, prosecutors charged that Rodney Eric Smith was responsible for the Dec. 1 murder. They presented evidence showing the Smith was with Hill in the hours before the murder, shopping at Home Depot for equipment to hang a 32-inch plasma television. They called DNA experts to testify that Smith’s semen was found at the crime scene, and they accused Smith of raping Hill before strangling her to death and then stealing the television and a laptop before driving off in her 2006 Nissan Altima.

"Three days later, on December fourth, the car was located in a parking lot in Prince George County, Maryland," said Sengel. "It was 300 feet from the front door of the apartment where the defendant lived."

Smith’s court-appointed defense attorney warned jurors not to jump to any conclusions, reminding them that all suspects are innocent until the commonwealth presents a case beyond a reasonable doubt. He tried to poke holes in the witness testimony, trying to catch inconsistencies between grand jury testimony and what they said on the stand this week. The defense’s theory of the case, according to court records, is that Smith was not present at the crime scene because he was on Van Dorn Street and later on a Metro train headed for his uncle’s house in Prince George’s County.

"The evidence will show that Mr. Smith was the last person seen with her," attorney Frank Aschmann acknowledged. "That doesn’t mean he’s guilty."

HILL JOINED THE United States Navy in 2004 at the age of 20 and eventually was hired as a secretary in the Office of Chief of Naval Operations — a job that required a security clearance to handle classified materials. She also prepared letters from Roughead to the Office of Secretary of Defense. Her MySpace page said she lived in Mississippi before moving to Detroit at age 11. Friends, who referred to Hill as "Tessa," described her as a fun-loving, outgoing and friendly.

"People were drawn to her," said Sheena Philiberg, a friend who worked with Hill in the Navy. "She didn’t come across as shy."

Philiberg testified that she had known Hill for six or seven months, and that the two formed a close friendship over that time — going to church together and arranging shopping trips together. On the day after Thanksgiving, she testified, she and Hill went to Best Buy in Alexandria to purchase a 32-inch plasma television for less than $800. She explained that Hill asked how much it would cost to have Best Buy install the television, she was told it would cost $100.

"She said she was going to get a friend to install it instead," Philiberg testified.

PROSECUTORS ATTEMPTED to make the case that Smith had been asked to help Hill install the flat-screen television in Hill’s bedroom in the sprawling EOS 21 apartment complex. Aside from the security-camera footage at Home Depot, they presented evidence that Hills’s bedroom had all the hallmarks of a flat-screen installation that had abruptly stopped. A line was drawn on the wall, and tools were scattered throughout the bedroom. But the police were never able to find the television, and prosecutors charged that Smith violently sodomized Hill before she engaged in what Sengel called "a protracted struggle for life."

"In his haste to leave the crime scene," said Sengel, "the defendant left behind some abundant and compelling physical evidence."

The prosecutor called experts who testified that Smith’s DNA was found on the inside of a condom that was found in a trash bag at the apartment. Aschmann countered that the presence of the DNA could be explained by the intimate nature of the relationship between Hill and Smith, and that prosecutors couldn’t prove that he is responsible for the murder. At press time, the jury has yet to render a verdict in the case.

"Speculation is not enough," Aschmann told the jury. "The commonwealth has to prove each and every element of each and every crime."