The Bureau of Investigative Journalism (TBIJ) published a report last week confirming that the Central Intelligence Agency appears to have briefly revived its controversial “double-tap” drone tactic in a Pakistani region in mid-2012.

Double-tapping refers to when a target is bombed multiple times in quick succession and usually results in the second strike hitting first responders and rescuers. The tactic is favored by the Islamist organization Hamas, according to a study released in 2007 by the Homeland Security Institute.

The strikes took place as part of a mission to kill one of al-Qaida’s few remaining senior figures, Yahya al-Libi, who was killed by a strike on June 4, 2012.

Respected Pakistani journalist Mushtaq Yusufzai, who regularly reports for NBC and local paper The News, was commissioned by the bureau to conduct the field investigation over a period of months. He spoke with an extensive list of government, Taliban, and civilian sources to gain a clearer understanding of what actually happened.

Yusufzai's findings seem to confirm what was widely reported by news agencies at the time -- five double-tap strikes took place around a single North Waziristan village in mid-2012, one of which hit a mosque, killing worshipers. Fifty-three people were reportedly killed and 57 were injured.

According to Yusufzai, no confirmed civilian deaths were reported by local communities, although a woman and three children were said to have been injured in one of the attacks.

“It is possible some civilians were killed, but we don't know,” said Yusufzai.

However, “a parallel investigation by

legal charity, Reprieve, reports that eight civilians died in a double-tap strike on July 6, 2012, with the possibility of further civilian deaths in a July 23 attack,” said the bureau.

According to Islamabad-based lawyer, Shazad Akbar, Reprieve's findings are based on interviews with villagers from affected areas and the strikes appear to have been targeting another senior militant, Sadiq Noor.

As the New York Times noted, American officials offered conflicting reports, stating that the only person killed in the newly confirmed double-tap strikes was top al-Qaida member, Yahya al-Libi.

The House and Senate intelligence committee, responsible for overseeing and reviewing the CIA drone strike program, reportedly viewed a video provided by the CIA which shows only the one al-Qaida member being killed.

TBIJ previously confirmed 11 double-tap strikes on rescuers between 2009 and 2011, along with one drone strike “deliberately targeting a funeral, causing mass causalities.”

According to the Bureau, between 2004 and 2013, an estimated 2,505 to 3,584 people have been killed in drone deaths in Pakistan, including between 407 and 928 civilians and between 164 and 195 children.

The number of civilians killed by drones can be hard to quantify at times due to -- according to administration officials -- Obama's practice of counting “all military-age males in a strike zone as combatants unless there is explicit intelligence posthumously proving them innocent.”

The United Nations special rapporteur on human rights and counter-terrorism, Ben Emmerson, previously stated that the double-tap practice, if found to be targeting civilians and first responders, could be considered a war crime.

"As a matter of international law, the U.S. drone campaign in Pakistan is ... being conducted without the consent of the elected representatives of the people, or the legitimate Government of the State," said Emmerson.

"It involves the use of force on the territory of another state without its consent and is therefore a violation of Pakistan's sovereignty," he added.

Emmerson is currently conducting an investigation of civilian casualties caused by drone strikes which will be presented in October to the U.N. General Assembly in New York. The investigation began after the U.N. Human Rights Council, following requests by Pakistan, Russia and China, asked Emmerson to do so.