The elderly patient was found with suspicious bruises, and staff members at the Fairfax County nursing home could not figure out what had caused them. County social workers thought the marks might have come from a hairbrush or some other blunt instrument.

Then another resident stepped forward and identified the perpetrator: one of the nursing home staff members charged with caring for the patient.

County social workers considered themselves lucky. They had a witness, and the staff member responsible was immediately dismissed.

But as social workers readily admit, such incidents often are shrouded in mystery. Frequently, abuse and neglect of the elderly and disabled go unreported. State officials estimate that only 16 percent of all incidents are reported.

"There's often a lack of understanding by many on what they should actually do," said Mori Yowell, a supervisor for the Fairfax County Adult Protective Services unit.

Throughout Virginia, there were 12,000 calls during fiscal 2003 reporting potential cases of elder abuse to local social service departments, according to state statistics.

Many of the 61 percent that were found credible involved what social workers call "self-neglect" -- when adults who live alone lose the capacity to take care of themselves. They often have extremely cluttered homes or lack proper medical support.

Yet many others are incidents in which caregivers -- either in private homes, nursing homes or assisted-living facilities -- inflict harm or don't adequately take care of patients or loved ones. Abuse includes sexual assault, confinement, mental and physical abuse and monetary exploitation. The victims are often women older than 60.

To increase reporting and protect seniors, the Virginia General Assembly this year passed a bill that expands the categories of people required by law to flag such incidents. In addition to teachers, doctors and social workers, emergency medical personnel, pharmacists, dentists and medical examiners now are required to report suspected incidents to county or state officials.

The legislation, sponsored by Sen. Janet D. Howell (D-Fairfax), is considered by many state officials to be the first substantial change in Virginia's elder abuse laws in 30 years. The change comes at a time when the state's assisted-living facilities have been under scrutiny for not protecting residents against other residents and some staff members.

"The idea is to better identify abuse against seniors," said Howell, who worked with Del. Adam P. Ebbin (D-Alexandria) to develop the bill.

The legislation also increases fines for people who do not comply with their obligation to report neglect or abuse.

In fiscal 2003, Fairfax County's Adult Protective Services investigated nearly 650 reports of abuse, neglect or exploitation of elderly or disabled adults and confirmed 359 cases, according to county officials. Prince William County officials said they received 379 reports, of which 112 were substantiated, in fiscal 2003. In Arlington County, 231 cases were reported and 120 were substantiated.

In Alexandria, where more recent statistics were available, 142 were referred and 137 substantiated in fiscal 2004.

Loudoun County officials said they received 320 reports of abuse in fiscal 2004 but were not immediately able to provide the number of those that were substantiated.

Local officials said the legislation that took effect July 1 will make a difference in catching some of the cases that used to go unreported, which many said is a challenge nationwide. There are nearly 2 million substantiated cases of elder abuse throughout the country each year, according to the Virginia Department of Social Services.

"We won't be able to tell until next year, but it should address some of the underreporting concerns," said Henriette Kellum, a supervisor in Arlington's Adult Protective Services unit. She added that the bill calls for additional training in identifying abuse.

But one aspect of elder abuse that the new legislation will not directly address is self-neglect. Some elders who live in dirty or cluttered homes and suffer from poor care are unaware of their own condition.

Because they are adults, they are allowed a certain level of privacy, preventing aggressive intervention. "Adults do have rights to privacy, and that sometimes presents challenges," said Yowell.

State lawmakers and local officials said that social service agencies will have to increase awareness about how people can help the elderly get assistance.

"We're going to have to look at establishing bridges to communities to make sure that many of our elderly get the help they need," Ebbin said.