The driver of a bus that crashed on a German motorway on Wednesday, killing four people and injuring many others, is being investigated for involuntary manslaughter and negligent bodily harm, the public prosecutor’s office said on Thursday. A spokesman for the office was unable to say whether the man, 62, had already been questioned. The double-decker Flixbus with 54 people on board, including two drivers, had veered off the A9 motorway near Leipzig on Wednesday morning and tipped onto its side. The bus company had previously reported that 55 people were on board. The police reported four fata…