With a few days left in 2016, Springfield's yearly homicide total is at its lowest mark in five years.

There have been eight homicides in the city this year, compared to 13 in 2015 and 17 in 2014.

In five of the eight homicides this year, authorities are still mulling whether or not the killer was acting in lawful self-defense.

Lt. Culley Wilson, who oversees the Springfield Police Department's violent crimes unit, said he's encouraged by the recent drop in homicides. He pointed to efforts to combat domestic violence, by the police department and others in the community, as a possible reason why.

Of the eight homicides in 2016, police believe only two were related to domestic violence.

"I think as we continue in the community to try to prevent domestic violence… it will affect us in the long run in our homicide rate," Wilson said.

Springfield's drop in homicides this year runs counter to a national trend. Sixteen of the 20 largest cities in the country saw an increase in homicides from 2015 to 2016, according to the Wall Street Journal.

Wilson said one reason why Springfield's homicide numbers are consistently low compared to bigger cities in the country is the relative lack of gang activity in Springfield.

"There are gangs in Springfield, no doubt about it, but we just don’t have that huge problem with fights over territory or drug sales as in other large communities," Wilson said.

Wilson said Springfield investigators are always looking for trends when they study homicides in the city, and how to prevent them.

There's one thing about the 2016 numbers that Wilson called "unusual," but he's not ready to call it a trend. In five of the eight homicides this year, police have said they know who the killer is, but charges have not been filed — this indicates authorities have not ruled out the possibility the killings were legally justified.

In one of those five cases, Greene County prosecutors have said they will not be filing charges. Three of the cases are being reviewed by prosecutors, and the other one is still under investigation, according to police.

"We’ve had some shootings this year that are just not totally black and white on what happened," Wilson said. "A person does have the right to protect themselves, protect their family, protect their property, protect their home."

Changes to Missouri's gun laws in September removed the permitting requirement for carrying a concealed weapon, expanded the state's existing castle doctrine and created a stand-your-ground provision such that people no longer have a duty to retreat before using deadly force.

Springfield defense attorney Shane Cantin said the new gun laws could lead to more years like 2016 where several of the homicides might not elicit criminal charges.

"The more guns that are carried, legally, the more likely people are to be in a situation or a confrontation where they feel the need to use it," Cantin said.

Cantin said the new gun laws might also slow down some investigations because prosecutors have these new regulations to consider.

"It certainly changes the landscape for a prosecutor," Cantin said.

It's unclear how recent changes in the law will impact pending homicide cases currently being investigated.

Wilson said the law changes aren't affecting how his detectives in Springfield do their jobs. He said the goal is still to investigate all homicides to the fullest and then leave it to prosecutors to make a determination on whether criminal charges are warranted.

Wilson said homicide investigations take a lot of time and effort. Having fewer killings this year has meant more time spent on older unsolved cases.

In November, prosecutors re-filed a murder charge against Terry D. Morrison for the 2011 killing of Pristina Tyner, citing new witnesses and "the continued investigative efforts of the Springfield Police Department."

Wilson said not being overloaded with new homicide cases helped his detectives find time to work on the Tyner case this year.

"We would have done it regardless of if we were overloaded or not," Wilson said. "But it helps."

Homicides in 2016

Jan. 3: Police say Brendan Riggs, 25, of Lebanon, was shot early in the morning in the parking lot of a Conoco gas station on Glenstone Avenue near Seminole Street. Riggs was transported to the hospital where he later died.

Police say the suspected shooter was contacted at the scene and taken to police headquarters for questioning. After interviewing the suspect and consulting with prosecutors, however, police released the suspect.

Police said last week the case was being reviewed by prosecutors.

Feb. 5: Police say Neal Williams, 43, of Springfield, was transported to the hospital on Jan. 28 with what were believed to be non-life-threatening injuries after he was stabbed in the 1000 block of South Thelma Avenue.

A week later, however, police say Williams died from "adult respiratory distress syndrome and septic shock due to healthcare-associated pneumonia due to post-operative complications of a stab wound."

In May, police said a suspect had been identified and the investigation was ongoing.

Police said last week the case was being reviewed by prosecutors.

Feb. 5: Police say Corey Kesner, 31, was shot and killed by Dan Rich, 39, in the parking lot of Remington's Corner shopping center in southwest Springfield.

Prosecutors said in October they would not be pursuing criminal charges in this case because Rich was reasonably acting in self-defense when he killed Kesner.

Prosecutor says no charges coming in February homicide in Springfield

Greene County Chief Assistant Prosecutor Todd Myers said the investigation showed that Kesner was armed with a screwdriver when Rich shot him.

Myers said Missouri's new stand-your-ground law did not have any bearing on this case.

Feb. 13: Jacob Merriman, 28, of Springfield, was shot to death about 6:45 p.m. Feb. 13 in the front yard of a home on West Avenue.

Police identified Trevor Brandt, 24, of Springfield as a suspect in the case.

Suspect released in homicide; could Castle Doctrine apply?

Brandt was arrested but released sometime on Feb. 14.

Greene County Prosecutor Dan Patterson said his office did not file charges in the initial 24-hour period in which a suspect can be held because of "the issues presented in this case, including but not limited to the application of the castle doctrine."

The castle doctrine allows property owners or renters to use deadly force at their home in self-defense.

Police said last week this case was being reviewed by prosecutors.

March 11: Police say Landon Bays, 18, of Springfield, was found lying on the side of the road with a gunshot wound at 7 p.m. on March 11 in the 800 block of West Catalpa Street. Bays was transported to the hospital where he spent the weekend in critical condition and later died.

Dad says man shot to death in Springfield 'always put others first'

Bays' mother told the News-Leader she believes her son was abducted from a nearby McDonald's, shot and dumped on the side of the road.

Police say this case is still under investigation. No one has been arrested or charged in connection with the killing.

To cope, family opens restaurant in honor of slain Springfield man

Aug. 17: Police say Edward Gutting, 44, rushed into a home on University Street in the evening on Aug. 17 and stabbed Marc Cooper, 66, to death.

Gutting was an instructor at Missouri State University and Cooper was a retired professor at MSU. The two worked together in the history department for three years, along with Gutting's wife who is also a professor.

Gutting has been jailed and charged with first-degree murder.

Case of MSU instructor accused of killing colleague moves toward trial

Police have said little publicly about a possible motive for the killing.

Nov. 14: The bodies of Rick Gene Chambers, 54, and Terry Lynne Porter, 36, were discovered Nov. 14 inside a home 315 N. Park Ave.

The police department said investigators believe it was Chambers who killed Porter before taking his own life.

Police believe Monday deaths were murder-suicide; identities released

Dec. 6: Police say Charlie M. Ingram, 42, was shot at a home on North Golden Avenue. He was transported to the hospital where he later died.

The resident of the home, Mark Glidewell, 63, told the News-Leader he shot Ingram when Ingram broke into his home.

Springfield man killed intruder: 'I never thought I'd have to shoot somebody'

No arrests have been made in this case. Police said last week the case is still under investigation.

Anyone with information on any of this year's homicides or the 2015 killing of Tyrone Gardner (last year's lone unsolved homicide) is asked to call the Springfield Police Department at 417-864-1810 or make an anonymous call to Crime Stoppers at 417-869-8477.