For over two months, Paramjit Singh, 48, a US green card holder battling a brain tumour and a heart condition, has been held in a detention centre by US immigration authorities.Mr Singh, an Indian passport holder, has lived in the US on a green card since 1994. He lives in Indiana with his family, who own a chain of gas stations. His wife and two children are US citizens.But Mr Singh now faces the threat of deportation. On 30 July, he was detained by immigration authorities at Chicago O’Hare International Airport while returning from a trip to India and has since been in their custody.US Immigration and Customs Enforcement (ICE) authorities have cited two decades-old cases as reasons for his detention, but Mr Singh’s family and lawyer say there are no active cases against him. They accuse immigration authorities of using old cases to delay his release and allege he lacks proper medical care despite a brain tumour and heart condition.”Paramjit Singh is not getting the medical help he needs. He is only getting medical check-ups,” his lawyer, Louis Angeles, told the BBC.The BBC has asked ICE for a response to these allegations.Mr Singh has regularly visited India without immigration issues, his niece Kiran Virk told the BBC. This time, his family waited seven hours at Chicago airport for his arrival.Ms Virk says immigration officials told them Mr Singh was detained over a 1999 case. He was held at the airport for five days despite family appeals, before being moved to a Clay County detention centre in Indiana.The case involves Mr Singh using a public phone without paying. Court records show he served 10 days in prison and paid a $4,137.50 fine. The conviction has blocked his US citizenship.Ms Virk alleges immigration authorities said at a court hearing that Mr Singh still faced a one-and-a-half-year sente …