Termination implant
From Memory Alpha, the free Star Trek reference.
The termination implant was a device attached to the brain stem of Vorta operatives of the Dominion. It was triggered by hand with a gesture that applied pressure with the index finger behind the right earlobe and the thumb under the jaw. When the device was activated (voluntarily) by the owner, it caused near-instant, painful death (though the Founders told the Vorta that death would be painless, this has proven not entirely true). Its purpose was to prevent Vorta – and the strategic information they possessed – from falling into enemy hands.
During his attempt to defect to the Federation in 2375, Weyoun 6 activated his termination implant in order to force the Jem'Hadar away from the runabout he was aboard with Odo. (DS9: "Treachery, Faith and the Great River")
- Presumably Yelgrun had a termination implant as well (or perhaps it was developed after his capture?), but for some reason decided not to activate it. It was known that Keevan chose not to commit suicide.
