NEW YORK (AP) - Medical-lab operator Quest Diagnostics Inc. will pay $302 million and one of its business units will plead guilty to misleading marketing practices for a diagnostic test as part of a settlement with the federal government.

In a statement Wednesday, the Department of Justice said the settlement represents one of the largest recoveries ever in a case involving a medical device.

Quest and its subsidiary Nichols Institute Diagnostics will pay the U.S. $262 million plus interest to resolve civil charges for misleading product claims.

Meanwhile, subsidiary Nichols will plead guilty to a criminal misbranding charge and pay a fine of $40 million.

Both civil and criminal charges involved marketing materials for a parathyroid hormone test. Quest also entered into a non-prosecution agreement.

Quest also agreed to pay various state Medicaid programs about $6.2 million to resolve similar misleading-marketing claims.

In its case, the government said the Madison, New Jersey-based company's subsidiary inaccurately marketed unproven advantages to the Nichols Advantage Chemiluminescence Intact Parathyroid Hormone Immunoassay.

"The American public has the right to expect medical-device manufacturers to make accurate claims in their labeling, especially when the failure to meet those claims could indicate that the performance of the device is suspect," said U.S. Attorney Benton Campbell, in a statement.

The investigation was sparked by the filing of a "whistleblower" lawsuit, which normally involves an insider coming forward with claims of wrongdoing. In this case Thomas Cantor will receive about $45 million under a provision that allows whistleblowers to share in the proceeds of the settlement.

Quest said it had been cooperating with the government since 2004 and has not admitted to the government's civil allegations, but agreed to the settlement "to put the matter" behind it. The payments have already been reserved.