Updated 09/19/11 – 8:35 p.m.

PORTAGE, Ind. (CBS) — An 18-year-old man has been charged with murder in the shooting death of Amanda Bach, of Portage Ind., over the weekend. Bach’s friends have described the suspect as the woman’s ex-boyfriend.

As CBS 2’s Derrick Blakley reports, Dustin McCowan, of Union Township, was charged with murder Monday afternoon. Authorities said Bach was shot in the neck.

Porter County Sheriff’s police said McCowan was being held without bond at the Porter County Jail, pending his initial court appearance on Tuesday.

amanda bach 0917 18 Year Old Charged With Killing Portage Woman

Amanda Bach, 19, went missing on Sept. 15, 2011. (Credit: Porter County Sheriff's Department)

At the high school Amanda Bach attended and the restaurant where she worked, those who knew here were dealing with their grief on Monday.

It was just last Wednesday that Bach worked her last shift at Quaker Steak and Lube Restaurant, in Portage, Ind.

“Wednesday, when she was leaving out of town, she was ‘Oh, I’ll see you Monday, ‘Berta.’ And I go ‘Okay,'” co-worker Roberta Mathis said.

But neither Bach nor Mathis had any idea that it would be their last goodbye. Bach left her home with a man last Thursday night around 10 p.m.

Bach’s car was discovered on Saturday in rural Wheeler, Ind., prompting an intense search, and her restaurant colleagues pitched in.

Co-worker Leslie Cook said, “On our days off, a lot of us went around to the search parties, hung up flyers, we made flyers to hang up around the restaurant. And some of us who were working the day, as soon as we got off, we went and helped out over there as much as we could.”

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But hopes were crushed when Bach’s body was found Sunday along the railroad tracks just 300 yards from the home of an 18-year-old man who some call her ex-boyfriend.

As CBS 2’s Pamela Jones reports, many friends said McCowan used to date Bach and Mathis remembers Bach mentioning an ex.

“She just said that she had an ex-boyfriend and that they were talking,” Mathis said.

It’s a relationship police want to know more about. They know the two were still friends and had planned to meet Thursday night when Bach disappeared.

Porter County Sheriff’s Police Sgt. Larry LaFlower said Bach and McCowan were known to “do what friends do. Hang out. We’re not sure what their activities were going to be that night.”

But police said something went horribly wrong. An autopsy on Monday revealed Bach died of a single gunshot wound to the front of her neck – an impact strong enough to sever her spine.

“The wound she suffered would have been instantaneous death. There would have been no suffering,” Porter County Coroner Chuck Harris said.

Asked if there was evidence of a sexual assault, Harris said, “preliminarily it does not appear that there was anything, but we are still testing all avenues.”

At Portage High School, where Bach graduated in 2011, grief counselors were available during classes and after school on Monday to deal with the outpouring of emotion.

Portage Township Schools Assistant Supt. Tom Taylor said, “those students that knew Amanda obviously are crushed by the news of what happened to her. And I think that their friends feed off of that, so there’s a lot of sadness and grief at Portage High right now.”

Her co-workers were still shocked and grieving, and were left to remember – and miss – Bach’s bright smile and always upbeat personality.

The restaurant’s manager, Iris Fernandez, said Bach “just had that kind of heart that she could reach out and just make anyone happier.”

Cook said, “You could break up, have a horrible day, the world would be falling apart, but you’d come in, you’d see her smile and she’d just, she would light up a room. She was really a beautiful young lady.”

Bach had planned to attend Indiana University Northwest in Gary in January.

An autopsy was being performed Monday afternoon and Porter County prosecutors were waiting on a preliminary conclusion on what caused Bach’s death before proceeding with charges against the suspect.

Authorities said the suspect was originally taken into custody by campus police at Indiana University Bloomington on Friday, where he was visiting friends. He was eventually transported early Sunday to the Porter County Sheriff’s office in Valparaiso.

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