New Haven Police have made arrests in two city killings this summer, the most recent on Friday, July 30, when New Haven saw its 15th murder of 2010.

The year’s 15 killings already surpass last year’s total of 12, and despite the two recent arrests, 12 other homicides this year are yet unsolved.

The latest murder victim, Michael Holland, 19, was found by police on a routine patrol Friday night in the Hill neighborhood. Holland had been shot in the chest and died shortly after officers found him.

According to New Haven Police Department spokesman Joe Avery, detectives from the Major Crimes Unit gathered information from witnesses pointing to a suspect and his possible location. Later Friday night, the NHPD SWAT team raided that location, also in the Hill, and found their suspect, Darius Jackson, 18, inside. Detectives charged him with Holland’s murder. Jackson has denied involvement in the murder.

On June 22, Marquise Baskin, the son of a city firefighter, was shot to death in the Newhallville neighborhood. One week later, the U.S. Marshals Fugitive Task Force arrested a suspect in the killing, Jermaine Scott, 30, in Middletown, Conn.

According to the Connecticut Department of Corrections, neither Holland nor Baskin had a criminal record. Police said both murders were the result of personal disputes.

Police have been frustrated over the past year by the reluctance of community members in violence-plagued neighborhoods to help police solve the crimes. NHPD Chief Frank Limon has made repeated pleas to city residents to assist police.

“The community should be outraged,” he said after an 11-year old boy was wounded in a shooting in June. “We would like for them to come forward and give us some information.”

According to police, the arrests made in the latest two murders resulted from extensive help from witnesses in the community. But detectives have had no such luck in virtually every other murder this year, solving only one of the 13 other killings so far.

In 2009, there were 12 murders in the NHPD’s jurisdiction, and the city experienced its lowest overall crime rate since the NHPD started keeping official records in 1990. If this year’s murders continue at their current pace, the city would be on track to have more killings than in any year since the early 1990s, when highly organized drug gangs controlled sections of the city.