The sister of the New York terror attack suspect has pleaded for him not to get the death penalty, claiming he was “brainwashed” and deserves a fair trial.

Umida Saipova spoke with Radio Free Europe (RFE) about her brother, 29-year-old Sayfullo Saipov, who is charged with carrying out the deadly truck attack. Authorities say Mr Saipov drove a rented truck through a bike path in lower Manhattan this week, killing eight people and injuring 12 in an Isis-inspired plot.

Ms Saipova told RFE that her family had not noticed any signs of radicalisation in her older brother. She claimed they had a “normal” conversation with him the day before the attack, in which he said he was eating his mother’s favourite pastry, and was on his way to pick up a client at the airport. Mr Saipov worked as an Uber driver after legally moving to the US in 2010.

“We don’t know who has brainwashed him,” Ms Saipova told RFE, from her home in Uzbekistan. “We don’t know his circumstances. We don’t know. Perhaps he’s become part of some organised group.”

She added that her mother, 50-year-old Muqaddas Saipova, had visited Mr Saipov in the US earlier that year and seen no sign of radicalisation.

“My mother said she would have brought him back to Uzbekistan had she noticed anything,” she said.

New York Truck attack Show all 6 1 /6 New York Truck attack New York Truck attack Investigators inspect the truck following the attack Investigators inspect a truck following a shooting incident in New York on 31 October 2017. Several people were killed and numerous others injured in New York on Tuesday when a suspect plowed a vehicle into a bike and pedestrian path in Lower Manhattan, and struck another vehicle on Halloween, police said. A suspect exited the vehicle holding up fake guns, before being shot by police and taken into custody, officers said. The motive was not immediately apparent. Getty New York Truck attack A paramedic looks at a body along the bike path A paramedic looks at a body covered under a white sheet along the bike path 31 October 2017, in New York. A motorist drove onto a busy bicycle path near the World Trade Center memorial and struck several people Tuesday, police and witnesses said. AP Photo/Bebeto Matthews New York Truck attack The truck driver collided with a school bus Authorities respond near a damaged school bus Tuesday, 31 October 2017, in New York. A motorist drove onto a busy bicycle path near the World Trade Center memorial and struck several people, police and witnesses said. Two adults and two children were on the bus at the time. AP Photo/Bebeto Matthews New York Truck attack A young girl reacts to the scene A young girl reacts as police officers secure an area following a shooting incident in New York on 31 October 2017. Several people were killed and numerous others injured in New York on Tuesday after a vehicle plowed into a pedestrian and bike path in Lower Manhattan, police said. 'The vehicle struck multiple people on the path,' police tweeted. 'The vehicle continued south striking another vehicle. The suspect exited the vehicle displaying imitation firearms & was shot by NYPD.' DON EMMERT/AFP/Getty Images New York Truck attack Police officers arrive at the scene Police officers arrive at the scene following a shooting incident in New York on 31 October 2017. Multiple people were hurt in downtown Manhattan, US media reported after police confirmed that they were responding to reports of a shooting. Police said they had mobilized to the scene in Lower Manhattan and that one person was in custody, giving no further details. DON EMMERT/AFP/Getty Images New York Truck attack Emergency personnel respond to truck attack in lower Manhattan Emergency personal respond after reports of multiple people hit by a truck after it plowed through a bike path in lower Manhattan on 31 October 2017 in New York City. According to reports up to six people may have been killed. Kena Betancur/Getty Images

The family did become worried, however, when they saw him sporting a full beard after his marriage in 2013. Ms Saipova described the family as “terrified” to see her brother adopting the facial hair style of some religious extremists. She said that he told the family the beard was an attempt to appear older, and to scare off potential muggers.

“I don’t know, honestly, how long it will take for his head to get rid of that poison,” she said of her brother now, “but I’m sure he will come to his senses, God willing.”

Isis took responsibility for the attack on Thursday, calling Mr Saipov a “soldier of the Caliphate.” According to a criminal complaint, Mr Saipov told authorities that Isis videos had inspired his attack.

The complaint also alleges he had about 90 videos and 3,800 images on his cell phone featuring Isis propaganda, including video of a beheading. Documents show he wanted to hang the group’s flag in his hospital room after the attack.

Trump calls New York attack suspect an 'animal' and signals scrapping lottery visa scheme

Mr Saipov has been charged with providing material support to a terrorist group and violence and destruction of motor vehicles. He made a brief court appearance on Wednesday, but did not enter a plea.

President Donald Trump called the suspect a “degenerate animal” and added that he “should get death penalty”, in a move condemned by several legal experts. Mr Trump also claimed that the US military had hit Isis “much harder” in the days following the attack.

Speaking to RFE, Ms Saipova begged US authorities to give her brother “a bit more time”.

“We don’t think he should be given the death penalty immediately,” she said. “We are hoping for a fair trial. We are ready to go there, if it’s possible, to talk to him.”