Ultimately, however, lead exhausts the system.
Usually typed, stamped "Secret" and often annotated by hand, the files are a paper trail of detective grunt work, leads exhausted, dead-ends encountered, sources checked and rechecked.
I pursued every lead and exhausted every option to find justice for my father.
But in asking Mr Abbas to lead his exhausted and sceptical people back into the tunnel of negotiations, and neglecting to switch on a light at the end of it, Mr Bush is asking a lot of the Palestinian moderates.
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Los Angeles County District Attorney Jackie Lacey told reporters Monday that familial DNA was used only as "a last resort" for serious cases in which all investigative leads were exhausted.
Once he rose, he meted out three more rounds of punishment that led an exhausted Dempsey to his second straight defeat.
The scene is France, 1415, the night before the Battle of Agincourt, in which (for those who need reminding) Henry V led an exhausted and outmanned English army to a surprising victory.
Over the next several years, numerous leads were exhausted, and several suspects were identified, though, ultimately, nothing came to fruition.
If a crime is serious and other leads are exhausted, authorities may try to find relatives of the perpetrator by looking for DNA profiles with many of the same markers.
