She declined to explain her disappearance, but did agree to let her family have her contact info, police said

Credit: Courtesy Doe Network

An Indiana woman missing since 1974 and presumed dead by her family was discovered Thursday in a small Texas town, living under an alias, state police said.

Lula Ann Gillespie-Miller, 69, was found in south Texas after she had been tracked down by Indiana State Police, who worked on her case for more than two years, according to a Thursday news release.

“It is believed that she had at times lived under an alias, but also along the way had been married and remarried,” Indiana State Police Sgt. John Bowling tells PEOPLE.

When found this week, Gillespie-Miller declined to explain her disappearance, but did provide her contact info to her daughter, Tammy Miller.

The news that her mother had been found alive came as a huge shock to Miller and left her reeling with a range of feelings, friend Debby Dyer tells PEOPLE.

“She was just hurt and angry and happy she was alive,” Dyer says. “She’s going through a roller coaster of emotions.”

Miller was just a young girl when her mother left, and doesn’t remember her, Dyer says: “Her entire life, she assumed this whole time her mother was dead.”

Gillespie-Miller was reported missing soon after she gave birth to her third child, when she walked away from her Laurel home and was never seen again, state police said in the release. She “felt she was too young to be a mother at the time,” police said.

Before disappearing, she “signed her children over to her parents,” police said.

The last time her family said they heard from her was in 1975, in a letter sent from Richmond, Indiana, police said.

Indiana State Police said their detective assumed the case in January 2014, after the Pendleton Post was contacted by the Doe Network, an organization that works on behalf of missing and unidentified persons.

While Detective Sergeant Scott Jarvis pursued a possible connection to a still-unidentified female body found in Richmond in 1975, “the investigation led [him] in a different direction,” police said.

“He began to investigate the trail of a woman with similarities to Lula Gillespie-Miller, who had lived in Tennessee in the 1980s, then later in Texas. Further investigation led Jarvis to a woman living in a small town in south Texas since the 1990s, possibly still living under an alias,” police said.

On Thursday, Texas Rangers, via Jarvis, contacted Gillespie-Miller at her home, where she confirmed her identity, police said, and agreed to allow her contact info to be released to her family.

Gillespie-Miller “could offer no explanation as to why she left her Indiana life behind,” police said – but wanted to make clear she “did not commit any crime by leaving her home in 1974, and still reserves the right to remain anonymous.”

Now Miller is now struggling with knowing the disappearance was a conscious choice, Doe Network head Todd Matthews tells PEOPLE.

But Miller is keeping an open mind because she doesn’t know why her mother left, he says. “It could be everything from trying to escape some type of family situation they feel is impossible, to mental illness to crime,” he says. “She might have been trying to protect her children for all we know.”

The two women might reunite someday, but so far nothing is planned, he says.

Bowling, with the state police, tells PEOPLE, “While Lula agreed to her information being given to her daughter, it doesn’t mean things will work out.”