The family of captive US government contractor Warren Weinstein called for ”date-specific confirmation” that he is still alive.

In a statement released Thursday, the Weinstein family said a video distributed last week by al-Qaeda in Pakistan does not prove that Weinstein is alive because there is no indication of when it was made.

Weinstein, 72, who has been held in Pakistan by al-Qaeda for more than two years, in the video calls on President Obama to release al-Qaeda terrorists in exchange for his release.

The video message featuring Weinstein, a former Peace Corps and USAID official, was sent to journalists and news services in Pakistan along with a link to a photo of a handwritten note. The testimonial letter is dated Oct. 3, 2013; it is not known when the video was filmed.

Weinstein, of Rockville, Md., was kidnapped in August 2011 outside Pakistan while he was working for J.E. Austin Associates, a private company that advises Pakistani businesses.

The United States has said it will not negotiate with al-Qaeda, which the U.S. considers a terrorist organization.

“Warren Weinstein is a scholar and a humanitarian who has spent his entire career working to improve the lives of men, women and children around the world,” his family said in the statement. “Prior to his abduction, he spent seven years in Pakistan working to improve local communities through projects related to dairy production, farming and health care. To be captured and held against his will after a life spent helping others, especially in the sunset of his proud career, is unacceptable. We urge the global community to help us bring him home.”

The family praised U.S. Rep. John Delaney (D-Md.) for his efforts on behalf of Weinstein.

“We must be relentless in our efforts to bring him home and we must maintain a sense of outrage and determination,” Delaney said in a statement issued Thursday.

Al-Qaeda has said Weinstein would be released if the US halted airstrikes in Afghanistan, Pakistan, Somalia and Yemen and it also demanded the release of all al-Qaeda and Taliban suspects around the world.