Elizabeth Konecsni traveled to Hungary this weekend with an urn of her sister's ashes and a list of questions about her sudden death.

Ancsa Konya's body was found under the Birmingham Bridge last month, hours after she wandered away from Ms. Konecsni's South Side home without explanation. Ms. Konya, a Hungarian native, was making her first visit to the United States.

The Allegheny County medical examiner's office told Ms. Konecsni it would be three months before her sister's toxicology results are known, an agonizing wait for her relatives who want to end the painful mystery.

"I have to face her children," Ms. Konecsni said before her trip. "I have no explanation. I know nothing."

Such is often the case for relatives struggling to come to terms with the death of a family member in which the cause remains undetermined.

A string of recent celebrity deaths has shed light on the importance of toxicology tests in determining a person's cause of death, especially when drugs are suspected.

The Los Angeles County coroner's office has said it could take six to eight weeks before music legend Michael Jackson's cause of death is known, "pending the results of toxicology tests," a familiar refrain in the wake of the high-profile cases.

Toxicology results, which can reveal critical clues about toxins in the blood, urine and other fluids, can take months to complete -- no matter if the dead received pop-icon status in life.

Fluid specimens change hands at least three or four times, as different investigators with different pieces of lab equipment conduct different types of tests, Medical Examiner Dr. Karl E. Williams said. Results must be interpreted and considered in the context of a person's medical history.

"It's nothing you can do in a couple of days," Dr. Williams said.

The tests can be speedier if investigators detect the presence of just one drug at a high level, he said, but they become more difficult when a person's fluids contain different levels of multiple drugs, which might be prescriptions taken in therapeutic doses.

It's up to forensic investigators to determine whether the drugs interacted to form a deadly combination.

Of the more than 1,000 deaths the county investigates yearly, at least 20 percent are drug-related, Dr. Williams said.

"The lesson of the drug deaths we've investigated is [that] there is virtually always more than one drug present," he said.

Since Mr. Jackson's June 25 death at age 50, news reporters have seized on rumors of his dependence on a host of prescription drugs and high-powered painkillers. Demerol, Oxycontin, Valium, Xanax -- news reports have speculated that he took them all. The Los Angeles Times also reported over the weekend that large amounts of the powerful sedative Diprivan were found at his mansion.

Former Allegheny County Coroner Dr. Cyril H. Wecht, who has worked on dozens of celebrity death investigations, said Los Angeles authorities will likely expedite toxicology test results for such a high-profile case.

"When you're Michael Jackson, you go to the head of the line," he said.

Investigators could already have test results -- with a full accounting of what drugs may have been in Mr. Jackson's body at the time of his death.

Yet they likely won't make those results public right away, Dr. Wecht said, because the investigation into how Mr. Jackson died -- and whether someone should face criminal charges connected to the death -- will take longer.

Most toxicology tests aren't given such a high priority, unless a prosecutor or police investigator is pushing for a quick turnaround, Dr. Wecht said.

In Allegheny County, more than 200 toxicology tests are "in different levels of completion," at any given time, Dr. Williams said.

In Ms. Konya's case, relatives said she was taking Xanax for depression, and multiple medications were found in her purse.

Ms. Konya, 57, seemed happy the day before she died, her sister said. She was scheduled to stay for two months, and the sisters planned to travel together.

In the weeks since Ms. Konya's death, Ms. Konecsni has returned several times to the scene near the tracks at the end of 22nd Street, where she died. The area is littered with debris and sleeping bags, chairs and makeshift campfire sites set up by homeless people who inhabit the area. Ms. Konecsni said she has talked to some of them but has learned little about why her sister died.

"I really wanted to help her," Ms. Konecsni said. "I was thinking I could give her something special -- to come to America."