ISLAMABAD, Pakistan — Pakistani officials said Tuesday that the police and security forces had found Shahbaz Ali Taseer, the son of a prominent former governor, alive in southwestern Pakistan five years after militants kidnapped him in a mystery that had riveted Pakistan for years.

Mr. Taseer, now in his early 30s, was kidnapped by Islamist militants on Aug. 26, 2011, in Lahore. Eight months before the kidnapping, his father, Salmaan Taseer, the governor of Punjab Province, was assassinated by one of his security guards, who had been outraged over Mr. Taseer’s campaign to alter the country’s harsh blasphemy laws.

The two episodes made the Taseers a public symbol of a Pakistani liberal establishment family that had been threatened by extremism. Speculation about Shahbaz Taseer’s health has continued over the years, with some assuming that he had been killed by his captors.

Mr. Taseer was found Tuesday evening in Kuchlak, a town near Quetta, the capital of Baluchistan Province, according to Anwarul Haq Kakar, a spokesman of the provincial ministry. The province has long been a battleground between the Pakistani security forces and ethnic Baluch separatists. It is also known as a stronghold for jihadist and sectarian extremist groups, including the Afghan Taliban.