Unidentified man in photo is a suspect in the homicides of two Indiana girls

— -- The man who was photographed on a nature trail around the same time two Indiana girls disappeared is now the primary suspect in their murder, according to the Indiana State Police.

The bodies of two girls -- Liberty Rose Lynn German, 14, and Abigail Jay Williams, 13, both of Carroll County -- were found on Tuesday near a creek, roughly three-quarters of a mile from an abandoned railroad bridge, near Delphi, where they were dropped off Monday to go hiking, and an autopsy revealed their identities.

Little is known about the man in the photograph at this time, police said.

Previously, he had been labeled a person of interest, and police said he might only be a witness to the crime. Today, that status changed, according to police.

"Since Wednesday, Feb. 15, law enforcement officers have distributed a photo of a person observed on the Delphi Historic Trail. The photo appears to depict a white male wearing blue jeans, a blue coat/jacket and a hoodie," a statement from the Indiana State Police read.

Police referred to "preliminary evidence" that led their attention to the man in the picture, without detailing what it was.

"During the course of the investigation, preliminary evidence has led investigators to believe the person, in the distributed photo, is suspected of having participated in the murders of Abigail Williams and Liberty German," the statement added.

The case has garnered great attention in the otherwise peaceful area of rural Indiana from which the girls disappeared.

Thousands of people gathered in Delphi on Saturday to take part in a motorcycle memorial ride to commemorate the lives of the two girls.

Organizers for the motorcycle rally estimated that more than 3,000 people took part in the ride, while hundreds of spectators watched, according to the Lafayette Journal and Courier, a local paper.

The paper said that the downtown area of the small city overflowed with motorcycles and cars, who registered for $20 per driver and $5 per passenger to ride from Office Tavern Bar in Delphi to Whiskey and Wine Saloon in Monticello, and that the funds were split between the families of the two victims.

ABC affiliate WRTV in Indianapolis reported that residents of Delphi were applying purple ribbons to their homes and storefronts show their support for the victims and their families.

A manhunt for the killer had intensified prior to this announcement, and local police have been assisted by the FBI in the case.

"We are asking help from the public to help identify him so he can be contacted regarding what he might have seen," state police said in a statement on Wednesday, regarding the man in the photograph.

Investigators told ABC News that a search warrant was executed at a home in Delphi on Thursday night, but it did not yield anything of value to the investigation.