NEW YORK — As the U.S. population ages, the elderly are becoming a prime target for financial abuse.

Sometimes the thief is a stranger who befriends a lonely senior. Other times it's a caregiver with sticky fingers. In still other cases, it's a telemarketer with "found money" to share, or even a member of the senior's own family who takes advantage of his or her declining mindfulness.

The National Center on Elder Abuse, a Washington, D.C., clearinghouse for elder rights advocates, estimates there may be as many as 5 million victims a year. But it acknowledges that no one knows for sure because there is no comprehensive data collection nationwide and because many seniors suffer in silence.

Linda Eagle, an expert on elder abuse, believes the majority of cases go unreported.

"Some of the elderly never know they've been scammed," she said. "Those who do are often too embarrassed to talk about it. Or they're afraid if they let on to their families, their families will see them as no longer capable of taking care of themselves and they'll take away their independence."

Eagle, president of The Edcomm Group, a consulting firm based in Fort Washington, Pa., that trains bankers on regulatory issues, believes that financial institutions need to become more aware of "red flags" of abuse so they can help protect their elderly customers. And she believes that baby boomers, who begin turning 60 this year, need to become more aware of the problem.

"Those baby boomers still fortunate enough to have parents have truly elderly parents who may be vulnerable," Eagle said. "And they themselves are growing older, so the problem will only increase."

Families whose loved ones have been victimized say the thieves prey on seniors' insecurities.

Patty Andresen, 57, of Newport News, Va., said that her 90-year-old father, John Patchin, got caught up in a telephone scam last year.

Her father, a retired army colonel who lives in a continuing care facility, got a phone call from someone who told him he had won $250,000 but that the money was hung up in a U.S.-Canadian customs office. If her father would send them $7,000 — in money orders — the prize would be freed and sent to him.

"A bell should have gone off that this was a scam, but it didn't," Andresen said.

Andresen, who operates a Visiting Angels in-home care service, said that she accidentally found out about the scam when she ran across the bank withdrawal slips while looking for something else.

"He said, 'I was hoping you wouldn't find it. I'm so embarrassed. It was so stupid,' " she said.

She believes that like many seniors, her father is "terrified he's going to run out of money" so when someone offers to send $250,000 in exchange for $7,000, "it doesn't log in that you don't get something for nothing."

Sherry Duksin, 54, of New York still gets angry when she talks about what fraudsters did to her mother, Eva, who died in her late 90s in January.

Duksin said that her mother had worked all her life and had been "fiercely independent" about her finances long after her husband died in 1969.

About 10 years ago, a woman approached her mother on the street as she headed to a senior center.

"The woman tapped her on the back and presented an envelope full of $100 bills and asked, 'Did you drop this?' " Duksin said. She hadn't, but immediately became engaged in a conversation with this seemingly honest person.

After her mother told the woman she had family in Israel that she worried about, the woman offered to introduce her to a "financier" who could help her earn 100 percent on her savings so she'd have the wherewithal to send money to her relatives.

Over the course of several months, her mother turned over $154,000 to the scammers.

"It stopped when my mother said, 'I have liquidated all my money, when am I getting this back?' " Duksin said. "She never saw or heard from them again."

The thieves were never caught and the money was never recovered, Duksin said.

Larry Meigs, chief executive of the Visiting Angels in-home care service franchise in Havertown, Pa., said that families need to be aware of how many different people play roles in a senior's life, including caregivers, cleaners, physical therapists, repairmen and a host of others.

Meigs recommends that families "remove the temptations" by making sure there's not a lot of cash in the senior's home, that checkbooks and credit cards are locked up and that there aren't a lot of documents lying around with the senior's Social Security number on them.

He also cautions that seniors sometimes are forgetful and think something's amiss when it's not.

"Frankly, lots of times things go missing, then show up later," he said.

Bob Blancato, coordinator of the Elder Justice Coalition in Washington, D.C., said elder financial abuse is often perpetrated by family members, and that this form is particularly difficult to uncover and punish.

"There's the stigma to admitting it's happening in your own family and the difficulty of potentially turning in a relative" for the crime, he said.

His coalition of organizations and individuals has been pushing for enactment of federal legislation to help combat elder abuse, whether physical or financial. The problem, he said, is that there are no national standards on what constitutes abuse nor national data on the extent to which it's occurring. Legislation has been introduced in Congress, but it remains unclear if it will be enacted this year.

"There has to be a comprehensive commitment made to getting the best kind of incident study we can," Blancato said. He also believes that "greater awareness and training would result in more reporting" which, in turn, would prompt more funding for prevention.