Less than two weeks into 2017, the city of Lynn had its first homicide. Hanky Betancourt, 29, was shot outside his home on Chestnut Street a month after he was released from jail.
His killing, which remains unsolved, marked the beginning of the deadliest year in Lynn and Essex County, where the city is located, in more than two decades.
The county covering the northeast corner of Massachusetts has had at least 26 slayings so far this year, mostly in Lynn and Lawrence, the region’s largest cities.
The surge in homicides in Lynn and Lawrence has come with a riddle — while the number of those cases is up, crime overall decreased in both cities, according to the police chiefs. And there appears to be no one cause that explains the spike in killings, though some point to a reduction in police spending and the opioid crisis as contributing factors.
“There is no commonality to any of this this year,’’ said Lynn police Chief Michael Mageary. “They’re unrelated. There’s no pattern to them. There’s no way to create a nexus from one to another.’’
Essex District Attorney Jonathan W. Blodgett, who oversees all homicide investigations in the county, said a definitive explanation for the increase in slayings is elusive, though drugs and untreated mental illness have been common factors.
“Those are two things that are really concerning to me,’’ he said.
So far in 2017, there have been 12 homicides in Lynn and 9 in Lawrence. Police in Lawrence are also investigating the death of a man who was shot in the head, though the medical examiner has not determined whether the shooting was a homicide or a suicide, Blodgett’s office said.
Though homicides are up, overall crime is down by more than 6 percent in Lawrence, according to police Chief James X. Fitzpatrick. In Lynn, data collected through November show the city had a 17 percent dip in crime from last year.
“Our crime rate has been significantly reduced, despite a significant reduction in budget, in manpower, and special units,’’ Mageary said. “I’ve been here 31 years. I can’t recall [crime] being that low.’’
Mageary said the city hasn’t been able to afford to hire new officers to replace outgoing personnel. There are 164 officers currently on the force down from 190 in 2015, according to the chief.
The decrease has forced Lynn police to disband some units, including a community policing team and a warrant task force, reduce the number of patrol officers on each shift, and remove some officers from investigative units, Mageary said.
“We’ve been sounding the alarm for several years about the cuts in the budget in that eventually there was going to be an impact. It was not going to be immediate but it would be gradual and it would be considerable and we’re seeing that now,’’ he said.
Juan Gonzalez, founder of the American Latino Committee, a group that works with the Hispanic community on the North Shore, called on Lynn’s incoming mayor, state Senator Thomas McGee, and other public officials to devote more money to policing. “This is an absolutely critical issue,’’ he said.
The department recently received more than $1.1 million in federal grant funds to hire nine new officers next year, though the grant requires the city to provide $963,500 in matching funds over three years, Mageary said. Even with the extra officers, he said, the department will remain short-staffed.
The last time Essex County had so many slayings was 1994, when 28 people were killed, according to data from Blodgett’s office. No other county has had as many killings in 2017 except for Suffolk County, which includes the city of Boston.
Nationally, cases of homicide and nonnegligent manslaughter rose by nearly 9 percent last year over 2015, according to FBI statistics. Violent crime was up 4.1 percent during the same period, the FBI said.
In Lynn, some of the killings have been brazen. In March, Mohammadreza Sina Zangiband, 24, an Iranian immigrant who lived in Salem, was fatally shot while making a food delivery. On Easter, Leonard Clement, 46, was shot and killed, and his friend wounded, after they left services at Zion Baptist Church.
Fitzpatrick, the police chief in Lawrence, said eight of the city’s homicides involved guns. Gun violence has spiked, he said, as drug dealers profiting from the sale of the powerful painkiller fentanyl buy firearms for protection.
After shootings spiked in the spring, Lawrence got help from federal law enforcement officers and State Police, Fitzpatrick said. Mayor Dan Rivera has also added more officers to the department, he said.
An investigation conducted with the Drug Enforcement Agency resulted in 40 to 45 arrests and the seizure of four firearms, Fitzpatrick said. On weekends, state troopers help patrol hotspots.
Blodgett said his office is fighting the increase in violent crime by sharing information with local police officers about individuals who they believe are most likely to perpetrate violence.
Nine of the killings in Essex County remain unsolved. In some of those cases, witnesses have been reluctant to help investigators, Blodgett said.
Laura Crimaldi can be reached at laura.crimaldi@globe.com.
