Published: Nov 27, 2012 3:23 PM EST
Updated: Nov 28, 2012 7:31 AM EST

PALO ALTO, Calif. (AP) - An executive vilified by Hewlett-Packard on allegations of an accounting ruse is stepping up his attack on the company accusing him.

In a letter to HP's board released Tuesday, former Autonomy CEO Mike Lynch defends his record. He also suggests Hewlett-Packard Co. is using the charges of financial shenanigans to cover up damage caused by its own mismanagement.

The missive represented Lynch's most extensive remarks since HP accused him last week of deceiving the company about the growth of Autonomy, a business software maker that HP bought for $10 billion last year. He had previously denied HP's accusations.

HP absorbed an $8.8 billion charge to reflect Autonomy isn't worth what the company paid.

In a statement, HP says it stands behind its allegations against Lynch and other former Autonomy employees.