Ernesto Torres was gunned down nearly two months ago, the bullets flying, his family suspects, because of his dispute with another man about a woman.

Like others whose loved ones have been killed in Camden this year, his mother, Cary Soldevila, hoped for a quick arrest. But the investigation, which came to a head over the weekend when an arrest warrant was issued for a suspect, took patience.

"I want peace in my heart," said Soldevila, 43, "that I can go to sleep at night and know that this person who destroyed my life is put away."

Torres, 22, is one of 17 people killed in Camden so far this year. Of those 17 homicides, 12 are unsolved. Investigators say they have promising leads in some of the cases. But witness intimidation, a lack of people willing to step forward, and a backlog of homicide cases from past years - including 2012, when a record 67 people were killed - have slowed progress.

On Friday, about 50 people marched through downtown Camden calling for justice in unsolved homicide cases. "No justice, no peace!" they yelled.

Some wore pins memorializing loved ones. Among them was Tina Santiago, 28, of Camden, whose 22-year-old brother, Mark Gonzalez, was found shot dead in a car last June. Santiago said she didn't have much hope that the killer would be found as the one-year anniversary of his death approaches.

"For me to expect to hear anything," she said, "it will almost be like for me to set myself down for failure."

Last year, 19 of 57 - or 33 percent - of homicide cases in Camden were solved, said Jason Laughlin, a spokesman for the Camden County Prosecutor's Office.

In Philadelphia, about 40 percent of homicide cases were solved.

While Camden has three fewer homicides this year than it did at this point last year, according to the county Prosecutor's Office, similar obstacles remain to solving them, said Lt. Frank Falco, of the county prosecutor's homicide unit. His unit pairs with police departments around the county to investigate slayings.

One of the factors in unsolved cases is the high number of homicides from the last two years - 124 total - which Falco said was "creating a backlog." To help alleviate that, Falco's unit has increased the number of its detectives from eight to 10 in the last three months.

The killings from 2012 and 2013 also came at a time of police layoffs and a sweeping transition in Camden, as what is now the Camden County Police Department replaced the disbanded city department.

During the changeover, the department "relied heavily" on investigative assistance from the county Prosecutor's Office, the FBI, and U.S. marshals, Camden County Deputy Chief Joseph Wysocki said in a statement issued Friday. Still, "at no time," he added, "has a detective from the Camden County Police Department not been assigned to a homicide investigation."

Witness intimidation has long been a big problem in solving cases in the city, authorities say, and it has grown worse with the proliferation of social media.

"Witnesses are intimidated in the city, because the city is a small city," Falco said. "Everybody knows everyone, and they have to live here. It's not easy for someone to come forward and give testimony.

"It's the hardest it's ever been."

Angel Cordero, 52, a community activist and former mayoral candidate, also said that coercion of witnesses by suspects is a predicament for residents.

"They're afraid, beat up, scared, and tired," he said. "And we have to find ways to wake them up."

The youngest homicide victim this year is Jonathan Garrett, a 20-month-old who died Feb. 1 of blunt-force trauma. The oldest is Pernell Earle, 71, who died April 10, also of blunt-force trauma.

No one has been charged in either case.

In contrast, two suspects were detained within days in the kidnap-murder of Fatima Perez, 41, though her family had alleged that police responded slowly when they reported her missing. Authorities denied that.

Carlos Alicea-Antonetti, 36, her landscaper, and Ramon Ortiz, 57, his employee, were charged in her slaying.

Perez, a mother of two, was kidnapped May 12 and buried alive, police said. While her body was found in Monroe Township, Gloucester County, the Prosecutor's Office in Camden County - where she was first reported missing - is planning to prosecute the case.

On Jan. 19, Confessor Santiago, 45, was beaten and body-slammed into a street, police said. He died 10 days later at Capital Health Systems in Trenton. Rasheen Kelly, 32, of Camden, was charged in connection with his slaying.

For Soldevila, the wait for an arrest in her son's slaying continues. Soldevila, who was among the people marching Friday in Camden, said she has known for some time who might have pulled the trigger. So, too, she said, have others.

"People know what's going on, and they don't speak. They're afraid to get involved," she said. "If people don't speak, it's going to keep happening. If they can get away with one thing, they're going to get away with so many other murders."