They held him for three hours and they let him go.

他们扣押了他3个小时才放走他。

《柯林斯英汉双解大词典》

After questioning him, they let him go temporarily.

在问他，他们暂时让他走。

youdao

The American of great wealth who had experienced the world said, "Let him go! As long as boys have the chance to show their talents, they are sure to become better."

这位饱经世故且富有的美国人说：“让他去吧！只要男孩子有机会展示他们的才能，他们肯定会变得更好。”

youdao

Then,they were to let him go. The pirates agreed.

VOA: special.2009.05.27

They let him go, but he says he was followed for a while.

NPR: Circus Brings Joy, Focus to Afghan Children

After three months they let him go.

BBC: Greece asylum: Journey through a broken system

He caught tubercular meningitis some time in 1958 and he was hospitalised for six months, and after that the last place they would let him go were smoky dives like The Cavern.

BBC: Looking back at the birth of The Beatles