A US federal judge on Friday ordered FTX founder Sam Bankman-Fried back to prison less than two months before his trial on fraud charges, revoking the disgraced cryptocurrency tycoon’s bail over alleged attempts to tamper with witnesses. Bankman-Fried, 31, has pleaded not guilty to charges of wire fraud and conspiracy to commit money laundering, as well as election finance violations, in connection with the spectacular collapse of his crypto firm last year. FTX and its sister trading house Alameda Research went bankrupt in November, dissolving a virtual trading business that at one point had been valued by the market at…