Former Enron executive Andrew Fastow arrives at federal court in Houston Tuesday for sentencing. ((Pat Sullivan/Associated Press))

A Houston judge showed leniency on Tuesdayin sentencing Enron'sformer chief financial officer to six years in prison.

U.S. District Judge Kenneth Hoyt could have sentenced Andrew Fastow to up to 10 years behind bars after he pleaded guilty in 2004 for his role in the collapse of Enron in a web of hidden debts.

On Tuesday, Fastow's lawyers asked for a reduced sentence of five years, citing his admission of guilt and his help in the U.S. government's successful prosecution in May of Enron founder Kenneth Lay and the former chief executive, Jeffrey Skilling.

The judge agreed that a reduced sentence was in order. "Prosecution is necessary, but persecution was not," saidHoyt. "These factors call for mercy."

In January 2004, Fastow pleaded guilty to one count of conspiracy to commit wire fraud and one count of conspiracy to commit securities fraud. At that time, he agreed to up to 10 years in jail.

Fastow was originally charged with 98 counts of insider trading, money laundering, tax violations and other counts.

He was alleged to have run complicated partnerships that allowed Enron to hide debt and boost its profits. He was also alleged to have shifted millions of dollars through the partnerships to himself, his family and his friends.

Skilling is due to be sentenced in October. Lay died of heart disease in July.

With files from the Associated Press