How BBC verified Hasina’s leaked audio ordering deadly crackdown during July Uprising
Earshot also detected Electric Network Frequency (ENF) throughout the recording, a frequency that's often present in audio recordings due to interference between a recording device and mains-powered equipment, an indicator that the audio has not been manipulated

The BBC has verified a leaked audio recording in which former prime minister Sheikh Hasina is heard ordering security forces to open fire on student-led protesters during last year's mass uprising.
According to the investigation and report jointly produced by BBC Eye and BBC News Bangla, this recording offers one of the most direct and compelling pieces of evidence linking the former premier to the use of lethal force against demonstrators.
The audio, which surfaced online in March this year, captures Hasina instructing an unidentified senior official to "shoot them on sight", referring to protesters.
In the report, published on Wednesday, citing a source, BBC reported that the phone call took place on 18 July last year while Hasina was at Ganabhaban in Dhaka.
Although the origin of the leak remains unclear, the BBC employed a rigorous multi-stage forensic process to verify its authenticity.
How BBC verified the recording
According to the report, the Criminal Investigation Department (CID) of police had previously matched the voice in the leaked clip with known audio of Hasina.
Additionally, the BBC commissioned Earshot, a forensic audio analysis firm, to independently examine the clip.
Earshot found no evidence of splicing, editing or artificial manipulation. The firm concluded that it was "extremely unlikely" the audio was fake.
The clip appears to have been recorded during a speakerphone conversation, as indicated by specific frequencies and background sounds.
Earshot also detected Electric Network Frequency (ENF) throughout the recording, a frequency that's often present in audio recordings due to interference between a recording device and mains-powered equipment, an indicator that the audio has not been manipulated.
The firm analysed Hasina's tone, breathing patterns, and speech cadence, finding no signs of artificial synthesis or manipulation.
British human rights lawyer Toby Cadman, who is currently an adviser to the International Crimes Tribunal (ICT), told the BBC, "These recordings are highly significant in establishing Sheikh Hasina's role. They are clear, properly authenticated, and consistent with other forms of evidence."
According to UN investigators, approximately 1,400 people were killed in the crackdown on protesters between July and August last year.
ICT prosecutors currently trying Hasina for crimes against humanity are expected to present the leaked audio as a key piece of evidence.
Hasina has been residing in India since she fled to the neighbouring country following her ouster through the mass uprising on 5 August last year.
Both Hasina and her party, the Awami League, have denied the allegations.
An Awami League spokesperson told the BBC that they could verify the authenticity of the audio clip. They further claimed that the recording "does not reflect any illegal intent" on Hasina's part.