His smooth voice could charm a woman who just happened to be walking by, although it earned him enemies in rival suitors. He excelled in math, but behavior problems set him back in school. He loved basketball and football but was too aggressive to master the finesse and fine points of the games.

Months after Robert Senquan Spencer turned 21, he was dead from a shotgun blast fired into his chest on a Southwest Washington street. Prince, or the Lone Wolf, as he was also called, became the District’s 80th homicide victim of 2013, slain a day after a dozen people were killed in a mass shooting at the Navy Yard.

Robert Spencer is seen in this undated photo. (Family photo)

The District had 103 homicides last year — a sharp increase from the half-century low of 88 in 2012. While the Navy Yard victims, innocents killed on a typical workday, were mourned by a nation, Spencer’s death was quieter. But it casts light on a persistent crime problem in one area of the city — along the volatile border with Maryland — where most of the Washington area’s killings occur and often get the least attention.

Spencer — who was 4 when his father was fatally shot in the District — died the way many there do: in a petty dispute. His was over a woman and a neighborhood beef, a killing that wasted a life, said Spencer’s 42-year-old mother, Tinamarie Spencer, who lives in Laurel and runs a construction business. She keeps a picture taken of her son at the morgue — smiling, she said — and goes to bed with a blanket with his face woven into the fabric, so she can hug him as she falls asleep.

[Map: 2013 homicides in D.C. and Prince George’s]

The mother of the young man, who had been both a victim and a perpetrator of crime, has a message to those in charge: “Get off your butts and get in the street and hear our pain. Hear the people who are crying, and do something.”

Tinamarie Spencer, 42, gets emotional as she discusses her son, Robert Spencer, in front of a blanket that bears his image at her home in Laurel, Md. Spencer, 21, was killed in the District the day after the Navy Yard shootings. (Jahi Chikwendiu/The Washington Post)

D.C. Police Chief Cathy L. Lanier said that despite fluctuations, the District is continuing a long-term trend of reductions in killings and violent crime. Although homicides in the city jumped 17 percent in 2013, they are still considerably down from the 248 a decade ago and the 454 in 1993. The statistics for 2013 are through Tuesday evening. Without the dozen lost in the Navy Yard attack, the District would be three slayings above the number in 2012. There were fewer gun robberies and assaults in 2013 but an increase in assaults involving guns, including shootings.

“I want it to go down,” Lanier said of the homicide count. “But I don’t think from where we are looking today that we should be sounding the alarm. Violence is actually going down, and we’re going to push the homicides down.”

In most of Washington’s suburbs, homicides remain low. Fairfax and Montgomery counties each reported nine killings last year, down from 2012. Alexandria had five, and there were none in Arlington County.

Elsewhere, homicides continued to decline in cities such as New York — which recorded 319 slayings as of Dec. 22, a 20 percent drop from 2012, giving that city one of the lowest per-capita rates in the country. Killings in Chicago were down 20 percent, and the number in Philadelphia plunged 38 percent. Baltimore recorded more than 230 killings, the most for that city in four years.

Prince George’s Officer Mohammad Ashkar keeps a photo of deceased Officer Adrian Morris in his patrol car, along with family photos. (Michael S. Williamson/The Washington Post)

Prince George’s Officer Jeffrey Braden stands over a man who was arrested after trying to flee the scene of a vehicle stop in the Hyattsville area. (Michael S. Williamson/The Washington Post)

In Prince George’s, homicides also continued to drop, from 64 recorded in 2012 to 57 last year. There were almost 100 in 2011. Robberies were down about 18 percent, and burglaries dropped nearly 12 percent. The homicide rate is the lowest it’s been since the 1980s, and for a jurisdiction once defined by crime, officials are pleased with the turnaround.

“Getting the reality out there as opposed to perception is really important,” said Prince George’s County Executive Rushern L. Baker III. “With these numbers being down, these are hard facts.”

Despite the strides, police on both sides of the District-Prince George’s border say they remain focused on the troubled strip. Most of the county’s homicides were clustered inside the Beltway and around the county line in communities that are more densely populated than the more suburban or rural parts of the county.

Authorities say criminals pounce on weak spots where two police agencies meet. “We have to make sure that our resources are coordinated,” said Prince George’s County Deputy Police Chief Hector Velez. “They see D.C. mounting an operation in Southeast D.C., and they’ll move into Prince George’s along that border. The thing that we have going is D.C. will notify us and we will move resources into that area as well.”

On a recent patrol near the border, Prince George’s County Police Officer Mohammad Ashkar pointed out a place where people often use PCP. He said he’s seen thieves target that area as well.

“They like to steal from our county and then hop back,” Ashkar said. About two years ago, two gangs of kids from the District and Maryland would hop between the jurisdictions to steal cars, the officer said. “They’d make a game out of it to see how many they can get.”

Police hope a new system designed to more quickly inform officers in both agencies about reports of crime along the border will result in quicker response times. Maryland’s Office of Crime Control and Prevention is also working to ensure criminals under parole and probation who frequently travel between the District and Prince George’s can be tracked. Through the first half of 2013, nine of the 33 suspects arrested in Prince George’s killings lived in the District.

Prince George’s County Police Officer Mohammad Ashkar patrols in a neighborhood known to be frequented by sellers and users of PCP. While crime is generally down in the District and Prince George's County, there's a persistent problem in the area where the two jurisdictions meet. (Michael S. Williamson/The Washington Post)

Lanier said her department also has more to do to curb domestic-related killings. She’s concerned with three homicides involving infants and young children, and seven violent deaths connected to bars or clubs, a trend she fears is the price for the city’s expanding nightlife scene.

Although killings have eased over the long term in both the District and Prince George’s, the impact on families has not. And as Robert Spencer’s death attests, the reasons are far more complicated than a drug deal gone bad.

Tinamarie Spencer traces her son’s anger to his father’s 1996 killing. He was 4 years old then, and good grades couldn’t keep him out of trouble. At 12, he was convicted in juvenile court of sexually abusing a girl, a charge his mother denied, and remained institutionalized through his 19th birthday. Still, he managed to get his high school diploma, and when he was freed from a foster home in Baltimore, earned a scholarship to a local university.

Spencer stayed in school until he was pulled over outside the city with cocaine in his car. The drugs belonged to his cousin, his mother said, but Spencer pleaded guilty to save his relative from accruing a third felony. He got probation but was kicked out of school, forcing his return to Washington.

Tinamarie Spencer, 42, gets emotional as she discusses her slain son, Robert Spencer, in front of a blanket that bears his image at her home in Laurel, Md. (Jahi Chikwendiu/The Washington Post)

Tinamarie Spencer, 42, sleeps every night with a blanket that bears an image of her slain son, Robert Spencer, who was killed the day after the Navy Yard shootings. (Jahi Chikwendiu/The Washington Post)

His conviction locked him out of the job market, and he tried to start a nonprofit group called New Reflections, using street kids to counsel other street kids. But more trouble followed — Spencer was charged with threatening to kill a D.C. police officer, then with stabbing a man during a dispute, an incident his mother said was self-defense. He was convicted of assault in the threat case, and the stabbing case was pending when he died.

The night of Sept. 17, Spencer had ventured to the Southwest corner of the District to meet with people helping with his nonprofit group. He lived miles away in Northeast, and his frequent entries into a foreign neighborhood were unwelcome, his mother said, especially by men protecting the local women. One such dispute grew over time, from a war of words to what would end with a shooting. Court documents say a man known as Goose walked up to Spencer, said, “What’s all that you saying?” and shot him in the chest. Police arrested a suspect two weeks later.

Spencer’s death was noted in a police news release and a few lines in a newspaper. A charging document outlining the case against the suspected shooter contains no hint of motive, or the complicated life led by the victim.

“I did everything I could to make him happy,” Tinamarie Spencer said. “But after all the failures and the unfairness and the injustices, none of it was good enough.” When she saw her son at the morgue, “he had a smile on his face,” his mother recalled. “Seeing that smile gave me peace. I said at least he can be with his father, and be happy.”

Ted Mellnik, Justin Jouvenal, Dan Morse, Rachel Weiner, Matt Zapotosky, Caitlin Gibson and Dana Hedgpeth contributed to this report.

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