The pensioner, who was not arrested, also had a Taser pointed at her.
Six police officers could face criminal charges after a 90-year-old woman with dementia was put in a spit hood, handcuffed and had a Taser pointed at her.
The Independent Office for Police Conduct (IOPC) said on Wednesday it is investigating the Metropolitan Police officers for potential criminal offences as well as gross misconduct.
The elderly woman was “distressed” and allegedly spat at one officer when they were called to her home in Peckham, south-east London, on May 9.
She was handcuffed, had a mesh spit hood placed over her head and a Taser trained on her before she was taken to hospital – still with the handcuffs and spit hood on – without being arrested.
It is claimed she was left with cuts and bruising to both wrists and one of her arms.
The Met referred the case to the IOPC, and a complaint was also made to the watchdog that excessive and unreasonable force was used against the woman, and accused officers of discriminating against the woman, who is black, due to her race, gender, age and disability.
Six officers are being investigated for potential breaches of standards of professional behaviour, and the possible criminal offences of assault and false imprisonment.
IOPC director Steve Noonan said: “We are concerned by some of the actions and decision-making of police officers involved in the detention of this elderly and vulnerable lady, and we recognise this incident has also caused community concern.
“It’s important that an independent investigation takes place to establish the full circumstances.
“We have been in regular contact with the lady’s family to update them on the investigation.
“Once it’s complete, we will decide whether to make a referral to the Crown Prosecution Service for a charging decision, and also whether any of the officers involved should face disciplinary proceedings.”
Investigators have viewed footage from body-worn video and hospital CCTV, as well as interviewing witnesses including medical staff.
The Metropolitan Police said the six officers are all based in the force’s Central South Basic Command Unit.
One has been suspended while the other five are on restricted duties, meaning they have no contact with the public while the investigation is carried out.
Detective Chief Superintendent Seb Adjei-Addoh, local policing commander in Southwark, said: “It is clear that this will have been a distressing experience for the lady involved and that the circumstances raise a number of questions that need to be answered.
“While I do not wish to pre-judge this process, officers know that they must be able to justify any use of force or restraint and we will expect that of the officers involved in this incident.
“They also know that we expect them to show compassion and to adjust their approach in real time according to the circumstances they are faced with.”