The MACC is investigating how RM42 million ( US $10.6 million ) went from SRC International into Najib 's bank account .
His arrest was part of a probe into SRC International , a former unit of state fund 1MDB .
The MACC is investigating how RM42 million ( US $10.6 million ) went from unit   into Najib 's bank account .
His arrest was part of a probe into SRC International , a former unit of state fund 1MDB .