A veteran American journalist visited the notorious My Lai Massacre site in central Viet Nam late last week, over four decades after he exposed the brutality of U.S. troops in the mass killings.

Seymour Hersh, 77, made the emotional visit to Son My Relic, also known as My Lai, in Quang Ngai Province's Tinh Khe Commune, on Friday and Saturday.

He said this was his first visit to Viet Nam since 1969 when he wrote a series of investigative articles exposing the 1968 My Lai Massacre and its cover-up during the war in Viet Nam – which ended in 1975.

During the visit, Hersh, joined by his wife and their two children, explored the relic and looked closely at the photos capturing and models simulating the horrific massacre, its sheer devastation and the loss of 504 innocent human lives.

American journalist Seymour Hersh (in white shirt) is seen at Son My Relic, also known as My Lai Hamlet, in Quang Ngai Province of central Vietnam during his visit to the country on December 20 and 21, 2014.

The journalist also talked to locals and historical witnesses about the event, which took place in Quang Ngai in March 1968.

His wife could not help but feel deeply touched at the sight of a canal in the middle of the relic, where local residents lay dead decades ago.

“I interviewed over 50 American soldiers who had taken part in the infamous carnage to gather information for my series. Through their recounts, I could feel the physical pain and mental agony incurred by the innocent civilians,” Hersh told Tuoi Tre (Youth) newspaper.

On November 12, 1969, Hersh reported the story of the My Lai Massacre, in which hundreds of unarmed Vietnamese civilians were murdered by U.S. soldiers, in a series of articles.

The reports prompted widespread condemnation around the world and undermined public support for the war in Viet Nam in the United States.

The explosive news of the brutal mass killings fueled the outrage of the U.S. peace movement, which demanded the withdrawal of American troops from the Southeast Asian country.

The series earned Hersh the 1970 Pulitzer Prize for International Reporting.

The veteran journalist later wrote a book titled “My Lai 4: A Report on the Massacre and its Aftermath,” which Italian director Paolo Bertola used to produce his 2009 film on the My Lai bloodshed.

Seymour Hersh, born in 1937, is an American investigative journalist and author based in Washington, D.C.

He is a regular contributor to The New Yorker on military and security matters.

Apart from his prestigious 1970 Pulitzer Prize, Hersh has also won two National Magazine Awards and is a five-time Polk winner and recipient of the 2004 George Orwell Award.