Actually how long after being exposed to marijuana smoke someone will test positive for ingestion, depends on their own rate of use and how they are being tested. For instance, someone who rarely if ever smokes will not test positive on a normal drug screen as soon as 3.5 hours after exposure. A more habitual user? That's where we will see the 60 day elimination.
Irregardless, the prosecutor has hit a major logical fail: she tested positive, but it can be eliminated from the body very quickly so she must have ingested prior to her arrest...? Does that sound like 2+2=5 to anyone else?