INDIANAPOLIS -- Investigators probing three separate 2007 Indianapolis slayings arrested four men Friday, including one man accused of being involved in all three killings and another accused in two, police said.

Samuel Fancher, 25, of Indianapolis, was arrested on preliminary murder charges in connection with the deaths of three people, including a teenage boy.

Police said they believe Fancher and Jerry Emerson, 32, of Indianapolis, were involved in the July slaying of Ryan Sampson, 16, and the September killing of Cornelius Stamps.

Investigators also believe Fancher, Coy Daniels, 26, and Lawayne Smith, 25, were involved in the November killing of Arnold Fitzgerald, police said.

Emerson, Daniels and Smith -- like Fancher -- were arrested Friday on preliminary charges of murder, Indianapolis police Sgt. Paul Thompson said. Fancher and Daniels already were in the Monroe County Jail in Bloomington on charges not related to the slayings.

Police said information from witnesses helped lead to the arrests.

16-Year-Old Killed At Abandoned House

Sampson and another boy were found shot July 30 in an abandoned house in the 2500 block of North Gale Street, police said. The second boy survived.

Thompson said he didn't know what led to that shooting.

Stamps Killed While Working On Vehicle

Police said Stamps, 28, and another man were working on a vehicle in the 2900 block of North Euclid Avenue when at least one male exited a white Chevrolet Lumina and shot them on Sept. 20. The second man survived the shooting, but Stamps was declared dead at a hospital.

A day later, police detained Emerson after seeing a car matching the Lumina's description at a home in the 3900 block of Sherman Drive, Thompson said. Police didn't arrest Emerson in connection with Stamps' killing at that time, but investigators considered him to be a person of interest in the case until his arrest Friday, Thompson said.

Fitzgerald Killed On City's West Side

Police said Fitzgerald, 31, and another man were shot in or near a house on the city's west side on the afternoon of Nov. 15.

A witness told 6News that three people exited a black SUV and shot Fitzgerald at close range outside the house. Fitzgerald ran into the back yard and collapsed before dying, the witness said in November, speaking on condition of anonymity.

However, police said in November that they believed a shooter or shooters entered the house and shot Fitzgerald and the other man there. Fitzgerald's body was found, police said, lying just inside a doorway in the back of the house.

At the time, police said gambling might have spurred an argument that led to the shootings. The second wounded man survived.