MUNCIE, Ind (AP) – The FBI joined the investigation yesterday into the sniper attacks that killed one person and wounded another along two Indiana interstates, and police searched fields, overpasses and roads for evidence.

Investigators turned over bullets and other forensic evidence to the Indiana State Police crime lab to determine how many and what type of weapons were used in Sunday’s shootings 100 miles apart, said state police Sgt. Jerry Goodin.

Sniper attacks on two pickup trucks on Interstate 65 near Seymour, 50 miles south of Indianapolis, killed a man and wounded another person early Sunday. About two hours later, bullets struck a tractor-trailer and a sport-utility vehicle on I-69. No one was hurt in that attack.

Authorities were considering the shootings linked “until proven otherwise,” Goodin said.

State police said they received more than a dozen calls through a tip line set up to help solve the shootings.

Sheriff George Sheridan said his department has added extra patrols. Electronic signs along Indiana highways also urged people to come forward and report anything strange they might have seen or heard.

“If you see something, say something, we’ll go out and investigate,” Sheridan said.

State police asked motorists who had travelled through the area during the past week to check their vehicles for bullet holes, saying a noise they dismissed as a rock might actually have been a bullet.

Police also collected video surveillance tapes from businesses near the shooting sites.

In addition, Indiana police consulted with authorities from Columbus, Ohio. In late 2003 and early 2004, a sniper there killed one person in a series of random highway shootings. Charles McCoy Jr who was arrested in 2004, pleaded guilty and was sentenced to 27 years in prison.