LOWELL -- A 60-year-old Lowell man who pleaded guilty last year to two counts of possessing child pornography pleaded not guilty Wednesday to six counts of possessing child pornography.

In Lowell District Court, Joseph Stasio, of 145 Bellevue St., had his bail set at $10,000 cash. Details of the case were not immediately available because the court file was impounded.

He is scheduled for a pretrial conference on Sept. 24.

Stasio was charged in April 2012 with two counts of possession of child pornography in a weeklong sweep of child-pornography suspects called "Operation Corral."

Stasio was among 32 people arrested during the sweep, conducted by state, local and federal law-enforcement agencies, the state attorney general and local district attorneys. The sweep ran from April 2 through April 6, 2012 throughout the state.

While that case was also impounded, court records indicate that after Stasio was indicted, he pleaded guilty in Lowell Superior Court to the charges in May 2013.

He was placed on probation for three years, but violated that probation and was sentenced in December to two years in jail with one year to serve, but served less than a year before being released.