。
The kidnapper showed no sign of giving up.
Literal
Kidnapper [topic-は] surrender-[attributive-する] sign [object-を] show-[negative-past-なかった].
気配 ('sign, hint, presence, indication') is a subtle word — often describing the barely-perceptible feel that something is present or about to happen. 降参する ('to surrender, give up'). 気配を見せる ('to show a sign of') is a useful collocation. The whole sentence has the tense cadence of crime or news reporting.