A former British Army doctor was found guilty of serious misconduct by medical watchdogs over the death of Iraqi detainee Baha Mousa.
Dr Derek Keilloh will now face possible sanctions against him working as a medic.
He appeared before the Medical Practitioners Tribunal Service (MPTS), and denied any cover-up.
He claimed he only spotted dried blood around the nose of hotel receptionist Mr Mousa after he was arrested and beaten by British soldiers in Basra in 2003.
Hooded with a sandbag for nearly 24 hours, Mr Mousa suffered 93 separate injuries including fractured ribs and a broken nose during the final 36 hours of his life in the custody of the 1st Battalion, Queen's Lancashire Regiment (1 QLR).
Dr Keilloh, the senior medic on duty who treated Mr Mousa, 26, on the night he died, repeatedly denied any knowledge of such injuries.
On Sunday the MPTS listed a series of failings in his conduct in not protecting detainees from mistreatment and ruled he acted dishonestly.
Today the tribunal hearing the case ruled these failings amounted to serious misconduct.
The tribunal has now retired to decide if Dr Keilloh should face any sanctions over his actions.
The MPTS has the power to suspend or strike off doctors they find guilty of misconduct.
The GP, who now works at Mayford House Surgery in Northallerton, North Yorkshire, should have been aware of the injuries to Mr Mousa - but failed to conduct an adequate examination of the body, the MPTS have said.
And knowing of the dead man's condition he then failed to assess other detainees or protect them from further mistreatment and tell senior officers what was going on.
And the MPTS said he engaged in "misleading and dishonest" conduct when, at court martials and a subsequent public inquiry, he maintained under oath he saw no injuries to Mr Mousa's body.
A public inquiry concluded Mr Mousa's death was caused by a combination of his weakened physical state - due to factors including the heat, exhaustion, his previous injuries and the hooding and stress positions he was subjected to by British troops - and a final struggle with his guards at the detention centre at Army HQ in Basra.
Dr Keilloh was, at the time, a 28-year-old captain new to his post of regimental medical officer of the QLR, having been in the job only eight weeks.
After a "very short" handover, he took over the medical team of the QLR at their HQ in the former headquarters of Saddam Hussein's Baath Party in war-torn Basra City.
A number of QLR soldiers had been killed in the city by insurgents and Operation Salerno was launched by the QLR against Saddam loyalists in the city.
On September 14, 2003 Mr Mousa and other detainees were brought in for questioning after being arrested at the Ibn Al Haitham hotel in Basra in the early hours of the morning.
At around 9.30pm the next day, Dr Keilloh was summoned from his medical post to the detention area because Mr Mousa had "fallen and collapsed".
Dr Keilloh and his team tried for half an hour to resuscitate Mr Mousa before he was declared dead at 10.05pm.
A £13m public inquiry into the incident led by Sir William Gage strongly criticised the "corporate failure" by the Ministry of Defence and condemned the "lack of moral courage to report abuse" within Preston-based QLR.
The MPTS panel hearing Dr Keilloh's case is expected to make a ruling by Friday.