Citing a reliable source, a report on "24 Oras" said the DNA sample from a body found at the site of the operation matched that of Marwan's based on test conducted by the US Federal Bureau of Investigation (FBI).
A photo exclusively released to GMA News by a SAF commando from the 84th Seaborne Force showed a bloodied cadaver, said to be that of Marwan, with an index finger missing.
Marwan, described as Southeast Asia's Osama bin Laden, was one of the most wanted terrorists of the FBI. He was blamed for many bombing incidents in the region, including the one in Bali, Indonesia, in 2002.
The FBI, which offered $5 million for information leading to Marwan's arrest, has earlier confirmed receiving a biological sample from the Philippines following the operation in Mamasapano, the report said.
How authorities confirmed Marwan's death
A separate "24 Oras" report said US authorities were able to confirm Marwan's DNA sample through his brother Rahmat Abdhir, who is currently locked up in Guantánamo Bay in Cuba for terrorism-related charges. He was arrested in California in 2007.
According to a US Department of Justice statement, charges of conspiracy to provide material support to terrorists, providing material to terrorists, contributing goods and services to a specially designated global terrorist, and false statements were filed against Rahmat.
Rahmat was reportedly providing funds and weapons for Marwan, whose presence in southern Philippines was first detected in 2003, a year after the deadly Bali bombing that killed more than 200 people.
Philippine government authorities have been firm on their position that Marwan was killed in the Mamasapano operation, which also left 44 elite policemen dead after they clashed with Moro Islamic Liberation Front (MILF) and Bangsamoro Islamic Freedom Fighters (BIFF) combatants in the area.
According to the preliminary report of the national police's Board of Inquiry that is looking into the clash, Marwan detonated booby traps around his safehouse when he sensed the presence of SAF commandos on the morning of January 25. The commandos, however, were able to shoot him dead.
The commandos then took a picture of his body and cut off a finger for DNA analysis and identification.
The clash with the MILF, however, shattered a three-year ceasefire between Philippine police and the Moro group and dealt a temporary setback to the ongoing peace talks.
According to one SAF commando who was part of the mission, the assault team of the 84th Seaborne Force rode a truck full of corns at 9 p.m. of January 24 to get to Mamasapano town. They were supposed to get Marwan at 3 a.m. before the Islamic morning prayer. A second SAF team, however, was delayed while crossing a river.
At 4 a.m. the next day, the 13-men team decided to pursue the mission without the others.
"4 a.m. na pero 13 pa lang kami nakakatawid ng ilog, kaya nag-decide kami kanain na namin. Kahit si Marwan na lang makuha kasi mag-uumaga na. Aalis na sila para magsimba," he told GMA News.
When the team reached Marwan's safehouse, the terrorist allegedly set off booby traps, but these failed to stop the SAF troopers, who managed to kill four people, including two women, inside the hut.
"Sa engagement sa kubo ni Marwan, alam ko apat patay doon. Dalawang babae, asawa niya 'yung isa. 'Yung isang lalaki, kapatid ng isang kumander doon," the SAF officer said.
The other terrorist SAF was after, Filipino bomb maker and Abu Sayyaf member Abdul Basit Usman, who lived near Marwan's hut, also fired shots toward the SAF men but he managed to escape with his guards and two Indonesians.
A man believed to be international terrorist Zulkifli bin Hir, alias Marwan, (inset) after he was killed by Philippine National Police (PNP) Special Action Force (SAF) members in Mamasapano, Maguindanao.