The wait for toxicology results can seem to take forever in some high-profile cases like the death of Michael Jackson, with several weeks going by before results are made public.

Even if initial alcohol results are known within a day or so, most medical examiners' labs will wait until the battery of screening tests, high-tech review and confirmation process is complete before making their results known, said Jeri D. Ropero-Miller, of the American Academy of Forensic Science's toxicology section.

"There's no set time period for toxicology cases to be completed - each case is different," she said.

Photos: Latest from the fatal Taconic Crash and reaction

Experts say toxicology results were done relatively quickly in the case of Diane Schuler - the West Babylon mother who caused the fatal July 26 Taconic State Parkway crash that killed eight. State police had asked the Westchester medical examiner to expedite the testing.

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Five members of a Long Island family were thrown from this minivan, which police said was traveling the wrong way on the Taconic State Parkway in Westchester. (July 26, 2009) Photo Credit: The Journal News Photo

The stunning results - released Tuesday, just nine days after the accident - showed Schuler had consumed high levels of alcohol and marijuana before the wrong-way crash.

"Even in high-profile cases, labs will usually take two weeks to finish their results," said Lawrence Kobilinsky, a top forensic expert at City University of New York's John Jay College of Criminal Justice in Manhattan. "I consider this pretty fast."

Among the tests considered:

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Blood, urine and other body samples. Collected usually at the hospital or during autopsies, these tests usually take 24 hours or less to complete and can provide initial signs of drug or alcohol use, and how long those substances were in the body before death.

These tests can also find evidence of poisoning by carbon monoxide, cyanideand other toxins. Mass spectronomy. Tissue samples are analyzed by a spectronomer to help detect substances, including drugs like cocaine, heroin and marijuana.This high-tech review, often in combination with gas chromatography, is often used to confirm initial screening tests or crime scene evidence.