Militants kidnapped Shamsudin Agha in Farah province's Anar Dara district on Tuesday, days after he led prayers condemning the practice of using suicide attacks, said provincial police Chief Abdul Ghafar Watandar.
Suicide attacks are one of the Taliban's preferred tactics in their assaults against Afghan and foreign troops. Most of the victims of such attacks have been civilians.
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Authorities recovered Agha's body on Wednesday night, Watandar said.
Violence by the Taliban and other insurgent groups has spiked this year to record levels. Attacks are up 30 percent from 2007, military officials say.
On Thursday, another suicide car bomber struck a U.S. patrol, killing eight Afghan civilians and one U.S. soldier and wounding 74 civilians, Afghan officials said.
Nearly 1,000 civilians are among the approximately 5,400 people killed in insurgency-related violence this year, according to a tally by The Associated Press of figures provided by Afghan and international officials. Most of the reported dead have been militants.
Elsewhere, U.S. troops killed four al-Qaida-linked militants during a raid in eastern Afghanistan on Thursday.
The troops were targeting militants who helped local Taliban leaders bring Arab and other foreign fighters into Afghanistan, the U.S. military said in a statement Friday.
None of the militants killed was identified.
WNYC's Brian Lehrer spoke to New York Times London Bureau chief John Burns this week about his time in Afghanistan and the state of the war there.