It sounded too good to be true: The parents of Shannon Marie Sherrill (search), missing for 17 years, received calls purportedly from their daughter hoping to reconnect. In the end, it turned out to be nothing more than a cruel hoax.

William Michael Sherrill, the father of the 6-year-old girl who was abducted in 1986 while playing hide-and-seek, collapsed in tears when he learned of the hoax only minutes before it was announced during a news conference Wednesday.

"I wasn't expecting this at all. I thought they were going to bring Shannon in here," Sherrill told reporters.

Police issued an arrest warrant for Donna L. Walker (search), 35, of Topeka, Kan., who faces a felony charge of identity deception and a misdemeanor charge of false reporting.

Police said Walker called the parents of the missing girl last weekend, claiming to be their daughter. She may also have contacted news organizations to spread word about the possible break in the case, said state police 1st Sgt. Dave Bursten.

Walker has not been arrested, and police were uncertain of her whereabouts. Neighbors have given varying dates when they last saw her in the red-brick condominium in a middle-class Topeka (search) neighborhood where she lived.

Bursten said Walker had given three different fictitious names to investigators in recent days.

"We don't know what her motivation was and it is impossible for us to guess," Bursten said. "We live in an age today where people like to receive attention."

Bursten told ABC News "Good Morning America" on Thursday that at first, authorities "thought it was very plausible" that the caller could be Shannon.

But over the next few days, the caller began postponing meetings with authorities, who wanted to conduct DNA testing. Authorities think Walker even called and posed as the caller's husband, offering more excuses on why a meeting had to be postponed, Bursten said.

Both Bursten and William Sherrill said the caller appeared to have researched Shannon's case.

"She had a bunch of real answers," Sherrill told ABC. "She knew stuff that nobody did. I didn't doubt it, not at that time, not at all." He recalled she did ask him what her birthday was, and, learning Shannon was born in August, said, "Good, it's close. Maybe I'll get to spend my real birthday with my real family."

The family had become the center of a media storm when the possible break in the case was reported and appeared emotionally drained when their hopes collapsed.

"It tore me apart," William Sherrill said Thursday. "It's like living 1986 all over again. .... I wanted it to be her so bad."

"I am very disappointed the case has taken this turn," said Boone County prosecutor Todd Meyer. "The case I want to prosecute was the case of an abductor, and the happy ending is the child coming home. Unfortunately that's not the closing argument I get to make."

Shannon vanished Oct. 5, 1986, outside her mother's mobile home in Thorntown, about 30 miles northwest of Indianapolis. Hundreds scoured fields and neighborhoods for days.

Jody Ames, an aunt of Shannon's, agreed that the last several days had taxed the family.

"It's been a very big roller coaster," she said. "We've been up and down, we've hoped for the best. We still hope for the best. We can only hope and pray."

Topeka police Lt. John Sidwell said officers there were helping in the search for Walker. Indiana State Police have said they expect her to be arrested soon.

"We know who she is; she can't hide forever," Bursten said. "Now the rest of the country will know what she's accused of and what she's done."