ARMADA, Mich. – Murder charges have been filed against James Donald Vancallis Jr., the man accused of killing 14-year-old April Millsap as she walked her dog in Armada in July.

Macomb County Prosecutor Eric Smith said Wednesday that Vancallis is facing charges of first-degree murder, felony murder and assault with intent to commit sexual contact.

If convicted on first-degree murder charges, he could receive a life sentence without the possibility of parole.

Web extra: Murder charges announced in Armada teen's slaying

"As the investigation progressed and intensified, the evidence led in only one direction: James Vancallis," Smith said. "My office intends to present physical, electronic and eyewitness testimony and evidence placing Vancallis at the scene of the murder with the victim at the time of the murder."

Vancallis is currently in custody on unrelated drug charges and had been the only person of interest named by police in Millsap's slaying.

James VanCallis Jr.

New information released Wednesday gives better insight into the night Millsap was found, and for the first time, 911 calls that got police to the scene were heard.

911 operator: "Is she on the trail?"

Caller: "No, she is off of the trail, tucked back in the woods. Her clothes are all taken off."

911 operator: "And you don't believe she's breathing?"

Caller: "I don't believe so, no."

From the beginning, police said Millsap had not been sexually assaulted, but it's indicated from the charges announced Wednesday against Vancallis that they believe he tried to rape her.

According to Armada's police chief, Vancallis stalked Millsap on the Macomb Orchard Trail, ambushed her from behind and used his motorcycle helmet to smash her head.

He reportedly took her to the woods and continued to beat and stomp her. Police matched the print marks on the teen's body to what they said are unique to the shoes Vancallis was wearing.

They said they believe he was intent on raping her and would have except for someone on the trail -- a witness.

Investigators and prosecutors said they have a witness who can identify Vancallis on the trail and that Vancallis stole Millsap's cellphone and backpack. A video camera nearby shows Vancallis speed away with Millsap's cellphone in his hand.

Macomb County Prosecutor Eric Smith didn't go into any detail as he announced the murder charge and the attempted sexual assault charge, nor did he address motive.

Vancallis will be arraigned Thursday morning.

Millsap's parents were at the charging announcement, but did not speak.

Web extra: Armada police chief on charges in teen's murder

"It's very emotional. It's just something we were waiting to hear," said Millsap's grandfather, Dennis Levans.