WARREN, Mass. – Each time a new lead emerges in the search for her 16-year-old daughter’s killer, Magi Bish feels like there’s a tug of war going on inside her chest.

“You have hope that it will end. You think, ‘Is this the person? Could this be him?’

“But you’re also emotionally exhausted. You fear. It’s like PTSD. You want answers, but you’re so afraid. It brings back everything about Molly.”

The Bish family has been on edge a lot recently.

Massachusetts state police spent two days last month questioning a Florida inmate in Molly’s death. Investigators have also sent 21 pieces of evidence for a new round of DNA testing. And prosecutors have agreed to ask the FBI’s behavioral analysis unit to review the case.

“We are very hopeful,” said Heather Bish, Molly’s older sister. “There is a certain responsibility when someone in your family is murdered. You have to find out who did it.”

Molly Bish was blue-eyed and blonde, bubbly and funny, everyone’s friend and her mother’s baby.

On June 27, 2000, Molly’s mother dropped her off at her lifeguard job at a rural pond in Warren, a town of about 5,000 in central Massachusetts.

Within eight minutes, she was gone. Molly’s lawn chair, water shoes, lunch and water bottle were on the pond’s small beach. Next to them were her police radio and an opened first aid kit.

Molly’s family believes her killer may have parked on a nearby cemetery road, watched her from a hill overlooking the pond, then lured her into the surrounding woods by pretending to be hurt.

Three years passed. In May 2003, a hunter’s tip led police to the blue bathing suit Molly was wearing. It was found in an area of woods known as Whiskey Hill in the neighboring town of Palmer, about five miles from where she disappeared.

Her remains were found scattered over 35 acres, her body ravaged by animals. No cause of death could be determined. Molly was buried Aug. 2, 2003, on what would have been her 20th birthday.

Her boyfriend was questioned. So were sex offenders who lived in the area. In all, investigators have talked to more than a dozen men, and dozens of witnesses went before a grand jury in 2004.

Still, no one has been indicted.

One of the things that torments Molly’s mother is the thought of a man she saw in the parking lot of the pond the day before Molly’s disappearance. The man was sitting in a white car, smoking a cigarette. Magi Bish waited until the man left, but didn’t think about him again until the next day, when Molly disappeared.

Her description of the man — middle-aged, with a mustache and combed-back hair — was used to make a sketch. Several men investigated by police have resembled the one in the sketch, including Rodney Stanger, a former Massachusetts man known to hunt and fish in the area. He is now serving a 25-year sentence in Florida in the fatal stabbing of his longtime girlfriend, Chrystal Morrison.

Stanger moved to Florida months after Molly’s disappearance. He was questioned in her death in 2008 but denied having anything to do with it.

Then, this past June, Morrison’s sister, Bonnie Kiernan, went to Florida to clean out the trailer Stanger and her sister lived in. She brought back items investigators in the Bish case are now examining, including hair bands and a 2000 firearms identification card with a photograph of Stanger that resembles the man in the sketch.

In July, state police went to Florida to question Stanger for a second time. Worcester District Attorney Joseph Early Jr. said Stanger again denied involvement in Molly’s killing. Police searched his trailer and brought back bags of evidence.

Alan Bushnell, a Florida lawyer who represented Stanger in the killing of his girlfriend, did not respond to telephone and email messages.

Despite the age of the case, Early said he is not discouraged.

Investigators are re-testing cigarette butts and other items found near the pond, near Molly’s beach chair and in the area where her remains were found.

“We know the science is getting better and people who might not want to speak to us around the time of the homicide — due to relationships, due to fear and other things — sometimes as time passes, they want to talk to us, they want to get something off their chest,” he said.

Since police first expressed interest in Stanger, Heather Bish has been struck by something Molly said several days before she disappeared.

Heather Bish said both she and her mother talked to Molly about safety because the pond was secluded and was known to be a popular spot for local fishermen and teenagers who hung out in nearby woods.

“Molly said to us, ‘Don’t worry, they’re just fishermen.’“