Ascension Parish sheriff’s investigators have linked the pistol used in a drug-related double slaying last month in Donaldsonville with four unsolved shootings in New Orleans in 2011 and 2013 that injured at least four people, deputies said Thursday.

Sheriff’s investigators believe Chad Nichols, 37, 178 Latino Drive, Donaldsonville, and Benny Booker, 29, 54054 Spellman Wall Road, Prairieville, were gunned down at Nichols’ Latino Drive mobile home in the midafternoon of Jan. 26 in a drug deal that may have turned into a robbery. Heroin was found in the home.

Chief Deputy Tony Bacala said investigators with Louisiana State Police and the New Orleans Police Department were able to match strike marks on shell casings recovered from the Donaldsonville shootings to those left at the New Orleans shootings.

A gun’s firing pin, which strikes the primer on the shell casing and sparks the gunpowder, is known to leave a unique mark on the casing. Law enforcement has used those marks for years to match weapons used in crimes.

Bacala said the casings were from a semi-automatic pistol. While the same gun was involved in all the shootings, it is not clear whether the same person fired the pistol in the New Orleans shootings or the Donaldsonville double homicide, or if different people have had possession of the weapon over the years.

Sheriff’s investigators do not have a suspect, Bacala said, but are following leads.

Frank B. Robertson, a New Orleans police spokesman, said investigations into the four shootings remain open.

“We cannot comment on the ballistic comparison that occurred in Ascension Parish,” Robertson said in an email Thursday evening.

Sheriff’s Maj. Kevin Hanna said Thursday that Nichols was found shot dead on the front lawn of his home in Donaldsonville. Booker, who worked with Nichols in his pressure-washing business, was found shot and wounded in the doorway of the home. Booker was taken to a hospital but was pronounced dead a short while later.

The were killed hours before a downtown Donaldsonville rally was to start. It was planned in reaction to other recent shootings in the west bank community.

Bacala said no one was killed in the four New Orleans shootings and that police reports do not indicate those were tied to the drug trade. But he said the 2013 shooting stemmed from an attempted robbery by two men who demanded cash and cellphones.

One man, who tried to flee the robbery, was shot but survived, Bacala said.

That 25-year-old man was shot twice in the body at the intersection of North Dorgenois and Aubry streets on May 2, 2013, in the 7th Ward near the New Orleans Fair Grounds, New Orleans police said.

In each of the three 2011 shootings, Bacala said, small groups of people told officers they were minding their own business, hanging out on a street when they were approached and people started shooting at them for no reason. He said investigators are keeping an open mind to the possibility of a drug tie.

“We have to recognize there may be more to the story than is told sometimes,” Bacala said.

According to New Orleans police, the shootings happened in different parts of the city: Central City, Treme and Gentilly.

Further bolstering sheriff’s investigators’ belief of a New Orleans-area tie to the Donaldsonville shootings is that Booker’s stolen station wagon was seen on surveillance cameras 30 minutes after the slayings headed east on I-10 past the LaPlace/U.S. 51 exit, Bacala said.

Booker’s white Dodge Magnum, bearing a Louisiana license plate YPC 682, had been stolen from Nichols’ driveway at the time of the slayings, deputies said.

A second vehicle, a 2006-2011 white four-door, 3 series BMW also was seen on surveillance video traveling with the Dodge Magnum, speeding through Donaldsonville away from Latino Drive.

Shortly after the Dodge and BMW left Latino Drive, witnesses reported seeing both cars getting on I-10 east at the Sorrento exit, Bacala said.

“We feel confident they left Donaldsonville and went directly to the interstate going east,” Bacala said.

The I-10/La. 22 interchange at Sorrento is the most direct route to I-10 from Donaldsonville.

Bacala said he could not say what other connection the Donaldsonville and New Orleans shootings might have besides the gun and the apparent direction of the getaway cars, saying it would only be speculation.

Hanna said a $7,500 reward is being offered for information about the Donaldsonville shootings.

Anyone with information may call the Ascension Parish Sheriff’s Office at (225) 621-4636, text 847411 to the sheriff’s anonymous tip line, or call Crime Stoppers at (225) 344-7867.

New Orleans Advocate reporter Jim Mustian contributed to this report. Follow David J. Mitchell on Twitter, @NewsieDave.