The 39-year-old woman boarded a Metro train at 9 a.m., exhausted from her overnight nursing shift. She headed home, away from downtown Washington, as the crowd on the Red Line thinned. She fell asleep.

In riveting testimony in a Montgomery County courtroom, the woman told jurors what happened next. At least two of them would soon be crying.

She awoke near the Fort Totten station. A man stood several seats away. They were alone in the Metro car.

"He approached me," she said, "and I saw a knife."

The criminal trial against John P. Hicks has addressed a question that stunned Washington-­area commuters when the case surfaced in 2016: How could someone be raped in broad daylight on a weekday Metro train as it was moving?

"That's exactly what did happen, ladies and gentlemen," prosecutor Donna Fenton told jurors, who are scheduled to begin deliberating Tuesday.

Tatiana David, an attorney for Hicks, did not deny a rape occurred. She said the police arrested the wrong suspect.

"He is an innocent man, wrongly accused of a crime that he didn't commit, because of a bad identification, and because of a bad investigation," David said of Hicks.

In their case, the prosecution focused on the victim's testimony, surveillance video from inside a Metro station, travel records from Hicks's SmarTrip card and DNA reportedly from Hicks that was pulled from a tissue found below a seat partially obscured by a partition in the corner of a train car.

The tissue, according to testimony, wasn't found until hours after the attack — a period in which the train in question took riders up and down the Red Line as Metro Transit Police detectives hunted for what amounted to a moving crime scene.

Part of their challenge was getting commuters off trains where the attack might have occurred and having those trains routed to end-of-the-line rail yards so the cars could be properly processed for evidence. The transit detectives pulled trains out of service three times after the reported attack.

"When we have to take a train out of service, it's a big deal," Detective Michael Morehouse testified. "My sergeant was on the phone with rail operations. They were like, 'You guys are crazy. You already have two trains out of service.' And we actually threatened them and said, 'If you don't bring that out to the Glenmont rail yard, we will go stop it wherever it's at and process it there.' "

Metro detectives had Hicks in custody by the end of the day of the reported rape, a swift arrest of a man they say had slipped out of the station and gone home.

In Hicks's trial this week, the victim walked to the witness stand on Wednesday. Put under oath and asked whether she would tell the truth, her first three words were barely audible.

"Yes, I do," she whispered.

The Washington Post generally does not identify individuals who say they were sexually assaulted without their consent, which the woman declined to give.

As she continued her testimony, her voice grew clearer. She described her job and her commute.

Although her rides home occurred during morning rush hour, she traveled against the commuting flow, taking the Red Line north of Washington into Montgomery County, where ridership in that direction gets sparse.

Fenton asked her to describe the morning of April 12, 2016.

She spoke of her train ride and how she awoke around the time she heard an announcement for the Fort Totten station. She realized there was only one other passenger in the train car. She pulled her cellphone from her bag, she testified.

"Are you going to Glenmont?" she said the other passenger asked.

She nodded and returned to her phone. The man asked if she had a boyfriend, she told jurors, before he suddenly showed her a folding knife with a four-inch blade.

"He grabbed me off from my seat," she testified, describing how she was pulled toward a partitioned seat at the end of the car. "I grabbed his knife to pull it away from my body . . . and I felt a burning sensation from my hand."

Her words, steady until then on the witness stand, grew halting.

"He said," she began, pausing for nine seconds, "he said, 'Pull down your pants.' "

She employed delicate words to describe the attack she said she endured, until Fenton gently asked her to be more specific.

She talked of pleading and praying.

"Please don't do this to me," she remembered saying. "Please don't hurt me."

"Just do what I say," she said the man said, "and I will not hurt you."

The woman took a noticeable pause in her testimony. Circuit Judge Cheryl McCally called for a 10-minute break.

Back on the stand, the victim spoke of how the attack ended several stations from where she said it had begun and of how she pulled a tissue from her bag and spit into it before the man finally left the Metro car. She walked out of the train onto a platform in a daze, she told jurors, as she said what she recalled hearing.

"She's not talking," someone said. "She's bleeding."

"Please, please don't leave," she recalled telling a stranger on the platform. "Please keep me safe."

A short time later, a Metro police officer was speaking with her, testimony showed.

The train was on its way back to Washington and detectives were about to start urgently looking at surveillance recordings and hunt for the train car she'd been in.

During cross examination, Samantha Sandler, another attorney representing Hicks, challenged descriptions of the attacker the woman had provided to police and at a hospital. He was an African American man, bald, no facial hair, and about 5-foot, ­4-inches to 5-foot, 6-inches tall, as Sandler recounted the woman's statements.

But as Hicks's attorneys had previously noted to jurors, their client was about five inches taller, was not bald and had facial hair. The victim countered that English is not her first language and that she had equated the word "bald" with closely cropped hair.

In her closing argument Friday, Sandler also questioned the forensic value of the tissue because it had been on the train floor for hours.

"How many people stepped on that tissue?" Sandler said to jurors.

Fenton, one of the prosecutors, countered that the detectives found the tissue in good shape and used it to extract DNA for testing.

Even before the trial, the Red Line case in 2016 drew attention.

Public notice of the rape aboard a train surfaced only after news reporters were tipped off to the incident more than a month after it occurred. Metro had not announced the incident to the public, outraging riders and officials.

After Hicks's arrest on the rape charge, it became clear in court filings that Metro Transit Police had identified him as a suspect in a separate Red Line incident of indecent exposure but had not immediately sought to arrest him.

In the rape trial, Hicks is charged with first-degree rape, first-degree sex offense and first-degree assault.