The mother of a Navy veteran is seeking answers after her son's body was discovered in his Texas apartment where officials said he had been dead for three years.

The remains of Ronald Wayne White, 54, were recovered Nov. 12, from the DeSoto Town Center Apartments in suburban Dallas.

White had been dead "for an extended period of time, up to when he was last known alive three years ago," the Dallas County Medical Examiner's Office said in a statement.

White's mother, Doris Stevens, said she last spoke to her son in November 2016. White was a defense contractor and traveled the world in that role, she said.

Stevens told NBC News Friday that her son had stayed in the United States to vote in the 2016 presidential election and had planned to go to the Philippines, where he had bought a home. White retired from the Navy as a senior chief petty officer in 2004, his mother said.

Ronald Wayne White. Courtesy Doris Stevens

White, who was single and had been divorced about 20 years, had recently sold his house in Glenn Heights, approximately 20 miles from Dallas, according to his mother.

Stevens, 70, said she grew concerned about her son in February 2017, as the two never went months without speaking. If he was in the United States, they would speak at least once a week and if he was out of the country, he would check in with her once or twice a month, she said.

By April 2017, when she could not reach him on his birthday, she said she knew something was wrong. Voicemail messages to his phone went unanswered, she said.

Stevens said she called the Glenn Heights and Dallas police departments to file a missing person report.

"They asked how old my son was and I told them and they said, 'You can't make a missing person report for a grown up,'" she said.

Neither department responded to requests for an interview Friday.

She said she knew that was untrue so she traveled from her home in Shreveport, Louisiana, to Dallas and visited both police departments multiple times.

"They didn't give me no kind of consideration," Stevens said through tears. She did not know her son had an apartment in DeSoto, otherwise she said she would have tried to access it.

Stevens, who lives on a fixed income, said she then tried unsuccessfully to convince her family members to pool money to hire a private investigator who could inquire with the State Department when her son's passport was last used and to look into his financial activity.

Last week, she said she received a call from one of her son's adult children informing her White was dead.

Stevens said she traveled last week to Dallas to visit the medical examiner's office. She said she asked the medical examiner how long her son had been dead. When he told her three years, she said her knees gave way.

"I lost control of my body," she said.

The medical examiner's office said a cause of death is not yet known and an autopsy with toxicology results can take up to 90 days.

Stevens said she will not stop digging until she knows what happened to her son. She believes the rental community where he lived is partly to blame for his body going undiscovered for as long as it did.

The DeSoto Town Center said in a statement Friday that White was frequently out of the country, and his bills were paid through automatic withdrawals from his account.

"Our maintenance personnel discovered his body when they identified and responded to a service issue at his apartment," the statement said. "We are cooperating with the police as they investigate this incident."

Stevens does not believe her son died of natural causes.

"It's just something weighing heavy on my heart," she said. "You're not supposed to bury your children."