Interrogators were so petrified at the grisly confession that they did not realise which murder he was talking adjacent to.
British aid worker Margaret Hassan, 59, was kidnapped and killed in Baghdad, Iraq in 2004.
For 12 years her lineage have endured a bungling police investigation that saw her convicted Jack the ripper escaping from jail with no idea where her body is.
A 23-year-old ISIS convict, called Amer, was brought in for questioning about the terrorist death cult also identified as Daesh, when he described the final days of Mrs Hassan and where her crucial is.
Colonel Ali al-Sudani, the head of Iraqi military intelligence in Tikrit, was reportedly baffled by the tidings amid a slew of unsolved killings and missing people, before he realised the jailbird was talking about Mrs Hassan.
Speaking to The Times, Colonel Ali al-Sudani, who led the cross-examination, said: «I have no idea why arrests have not yet occurred.
«We bear all the necessary information. My commanders keep telling me it is a matter if time.
«What are they stop for? Waiting foal these months, perhaps they are scared, or confounded.
«Or perhaps they have forgotten Margaret Hassan.»
Amer was reportedly freed by Tikrit courts a fortnight ago on principle of forged acquittal documents and little has been done to investigate his confession.
Colonel al-Sudani added: «He was…anchor by family to local Baathist groups here and then had personally served with Hassan’s kiilers with the Daesh.
«He advised ofed everything: who kidnapped her, where she was held, who killed her, where she is buried.»
The aid wage-earner, who had joint British, Irish and Iraqi nationality, was the director of charity Distress International in Iraq and was on her way to work when she was abducted on October 19, 2004.
Hours later she arrived in a video released by her captors who called themselves an «armed Islamic organize».
Further footage emerged including scenes so harrowing that Arabic small screen station al-Jazeera refused to screen rts of the videos.
Her abductors cowed to hand her over to Ken Bigley’s killers Abu Musab al-Zarqawi, but it’s unclear if the turn ever took place.
It’s believed she was killed in November 2004.