People accused him of being a snitch. A man he was to testify against called him twice on the phone. "Why are you going to [expletive] me over?" the man said.
Then, in October of last year, two men pumped at least six bullets into him in what police believe was an attempt to silence him. He survived and, undeterred, promised to testify when it was time.
Dowery was sent to live outside Baltimore and, as the case spiraled into a federal prosecution, he waited to take the stand.
He came home to East Baltimore at Thanksgiving to share a meal with his large, close-knit family. After dinner, he went to a corner bar. There, someone fatally shot the 38-year-old father of nine.
"He was assassinated," said Assistant Federal Defender Joseph L. Evans, who represented Dowery. Evans said he based that belief on the earlier shooting of his client.
City police and the FBI are investigating the killing of Dowery and whether it was related to his cooperation with authorities. Police would not give details about the night Dowery died.
It's unclear what impact his death will have on future trials of defendants against whom he was planning to testify.
Maryland U.S. Attorney Rod J. Rosenstein said he would bring the weight of his office, with a possible penalty of a death sentence or life in prison, down on anyone who killed or contracted to kill a witness.
The killing of Dowery has raised questions about what protection is given to Baltimore's witnesses - and what can be done to keep them from putting themselves in harm's way.
Dowery had been given witness assistance.
After he was shot and wounded in October 2005, city police and prosecutors persuaded him to go to a safe house and helped him move out of Baltimore.
And when the U.S. Attorney's Office indicted the case in which Dowery was a witness, he began receiving money from federal agents for living expenses. Sources did not say how much or for how long.
Bartlett Avenue was a dangerous place for Dowery. It's where he had become a witness to the October 2004 killing, where he had been shot in his own doorway in October 2005 and where two of the men he had planned to testify against had lived before their arrests.
Local and federal authorities said they warned Dowery not to return to his old neighborhood. Yet Bartlett Avenue is where he was killed.
One of the chronic problems with protecting witnesses, whether at the local or federal level, is persuading them to stay away from their familiar surroundings.
"We cannot take their safety more seriously than they take their own safety," said Gloria Luckett, a victim-witness assistance coordinator for the Baltimore State's Attorney's Office.
Evans said his client might not have fully understood the danger he was in, despite the earlier shooting.
"It's not appropriate to blame John Dowery," Evans said, predicting there would be "a lot of covering one's backside" for what happened.
Dowery's tangle with the justice system - and perhaps with street justice - began Oct. 13, 2004, as he stood in his doorway at 604 Bartlett Ave.
His friend James Wise walked up and told him about a plan to rob the drug dealers on the corner. Dowery advised Wise and Wise's younger companion against the robbery, but he watched as they walked down the street and committed it anyway.
Then Dowery said he saw the drug dealers' bosses, two brothers who controlled the small, tough neighborhood, hop into a white Lexus and chase after the robbers.
Later, the bosses walked past Dowery and, he said, they spoke about a shooting. One man said he "got" the victim six times in the chest. "I'm tired of killing [people]," he said, according to Dowery.
When Dowery read in the newspaper that it was his friend Wise who had died, he decided to tell police what he knew. He also told them he would testify.
The men Dowery identified were Tamall Parker and Tracy Love, who lived just a block away on Bartlett.
In his taped interview with police, Dowery said he wanted justice for his friend. "So, basically, I'm just coming to give you information on my own," Dowery said. "It's not like y'all promised me anything."
Authorities did say they would consider Dowery's help when they sentenced him in his own case. About eight months before Wise was killed, Dowery had been indicted on federal charges of being a felon in possession of a handgun, which carries a maximum prison sentence of 10 years.
After agreeing to cooperate, Dowery told police he was worried about his safety: "Yeah, somebody approached me about saying, yeah, you snitching on us."
But Dowery didn't leave Bartlett Avenue.
The short road of two-story rowhouses, some vacant and dilapidated but some cheery and already decorated for Christmas, was a place that Dowery knew well, his family said.
His mother has owned a house nearby for decades, and many other relatives are well within walking distance.
Dowery was living at 604 Bartlett in December 2003, the time of his most recent arrest, for drug possession. He later pleaded guilty. Court records show he had never been convicted of a violent crime or of drug dealing.
Since his friend Wise was killed, Dowery seemed to have turned his life around. He hadn't gotten into any legal trouble and was regularly working. Evans, his attorney, said he was winning his battle with a heroin addiction.
"I liked John Dowery an awful lot," Evans said. "He was a very engaging guy. He was a person who struggled every day of his life with poverty and addiction. And he was a person who nonetheless carried himself with a great deal of poise and dignity."
Dowery's longtime girlfriend and children described him yesterday as a committed father. John Dowery III - so much the spitting image of his namesake that he said people called them twins - said his father was doting and caring.
He particularly spoiled his youngest, 5-year-old Kayiah. Yesterday at her grandmother's house, she wore a red-striped polo shirt of her father's, so oversized on her tiny body that it became a dress.
"Anyone can be a dad," said John, 19, "but I had a great father."
Dowery was returning home to 604 Bartlett after working the midnight shift Oct. 19, 2005, at the McCormick spice factory.
As he went to open his door, he sensed something, turned around and was confronted with armed men, he later told police.
He ran, but the men chased him around his yard and a neighbor's, firing shots all the while. Dowery was hit in his back and both arms and legs by at least six bullets. Police found 12 shell casings at the scene.
Dowery made it into his house and collapsed on his couch, where his son John found him.
Police reports link that shooting to the fact that Dowery was a witness to the Wise killing. Police arrested James Dinkins, who lived on Bartlett, and Damien West and charged them with the shooting.
Now Dowery was a witness for a second time.
His shooting stoked the concerns of city police and prosecutors, who persuaded him to move into a city safe house, a temporary residence at an undisclosed location.
Several weeks later, with assistance from the city, Dowery settled into an apartment outside Baltimore.
Come January, Dowery kept his promise to testify against Parker and Love.
"He was courageous and committed to justice," said Margaret T. Burns, a spokeswoman for the Baltimore State's Attorney's Office. "He did the right thing under very difficult circumstances."
Dowery took the witness stand in Baltimore Circuit Court and told jurors what he had seen and heard on Oct. 13, 2004.
He also told them about two phone calls in which Love urged him not to testify.
Dowery was barred from discussing his own shooting because there was not enough evidence to prove it was linked to Parker and Love.
Assistant State's Attorney J. Christopher Nosher described Wise's killing as an example of how "the laws of the drug trade reign supreme." The defense attorneys called Dowery and other witnesses unreliable.
In the end, even with Dowery's testimony, jurors couldn't agree on a verdict.
But this summer, federal authorities indicted Parker, 20; Love, 22; and two others, Dinkins, 34, and Cornell Booker, 23, on charges of conspiracy to distribute heroin.
Dinkins also is charged federally with firing a gun as part of drug crime on Oct. 19, 2005 - the date Dowery was shot and wounded.
Federal prosecutors would not discuss the specifics of the case, which is set for trial in March. Dowery's attorney said he had agreed to help with the federal case.
Damien West, 27, remains charged in Baltimore Circuit Court with shooting Dowery in October 2005. He is scheduled for trial in February.
All five men have been held without bail since their arrests.
Though he had been threatened, shot and uprooted, Dowery continued doing well in his life, his relatives said.
This spring, he attended the Patterson High School graduation ceremony for his two oldest sons, Blandon Dowery, 17, and John.
"He was proud of us," John said of his father. "But we were proud that he was there to support us."
Recently, he began working as a maintenance man at a downtown hospital. Relatives said he could not be kept from his family. And his family, for the most part, was on and near Bartlett.
"I don't believe that he was visiting his mother every day," Evans said. "For him to show up for Thanksgiving dinner, I'm sure he thought he could do it."
Dowery feasted at his aunt Joyce Garner's house on Bartlett. Garner said he was upbeat and spiritual. As she cooked for the 20-plus people who came through that day, he came into the kitchen to talk with her.
He told her: "God has got everything. Don't worry about it," she said. "He had made peace with God."
After dinner, he walked to the Kozy Korner bar in the next block.