Complex sentence: In June 2003, he stepped down as the Green party's environment spokesperson after it was revealed that he held shares worth $70,000 in a number of oil exploration companies which he had inherited when his late mother had left him $1.3 million in her will.
Split into simpler sentences: In June 2003, he stepped down as the Green party's environment spokesperson after it was revealed that he held shares worth $70,000 in a number of oil exploration companies. His explanation was that he had inherited the shares when his late mother had left him $1.3 million in her will.