New federal charges in the Starkey Laboratories fraud case add allegations of filing false tax returns against two former company officers.

The charges appeared in a superseding indictment Wednesday that tacked on four new criminal counts to the 30 previously filed against three former Starkey executives and two Starkey associates.

In addition to fraud and embezzlement charges filed in September, fired Starkey President Jerry Ruzicka and fired Starkey Chief Financial Officer Scott Nelson were charged with significantly underreporting their income on tax returns filed in 2010 and/or 2014.

The new criminal charges are part of an ongoing saga that came into public view in September with the abrupt firing of Starkey’s top four executives, two executive secretaries and about 15 managers. Intense finger-pointing followed, with Ruzicka and others accusing Starkey owner Bill Austin in lawsuits of wrongfully firing whistleblower employees.

Then federal authorities charged Ruzicka, Nelson, another executive and two suppliers of embezzling more than $20 million from Starkey via the use of dummy companies, fraudulently transferred restricted stock and secret bonuses and insurance policies — all allegedly issued without the knowledge of Austin.

All five defendants have pleaded not guilty and say Austin knew, approved of and benefited from all transactions.

According to the new charges filed Wednesday, authorities have charged Ruzicka with underreporting his income on tax returns filed in 2010 and 2014.

Court documents said his “adjusted gross income was substantially in excess” of the $782,693 he reported in 2010 and the $1.721 million he claimed in 2014.

Nelson is accused of reporting $567,979 on his 2014 return, much less than his real income, the documents said.

Nelson also is accused of submitting a “false and fraudulent” corporate tax return on Starkey’s behalf for the 2013 tax year.

According to court documents, Nelson claimed that Starkey Laboratories was entitled to receive a $12.9 million deduction. But the government charges that the deduction was based on fraudulent payments of restricted stock from a Starkey-related company, Northland Hearing, that were given to Ruzicka, Nelson and another unindicted executive.

Ruzicka and Nelson, nor their attorneys, could be reached for comment, but they have said in the past that the two men are innocent and will fight all charges.

Starkey spokesman Jon Austin said Wednesday’s additional criminal charges “shed additional light on the lengths to which the [accused] went in an effort to conceal their misconduct.”

He added that Nelson’s “false corporate tax return was used to cover up the timing of payments on a $15 million [stock] theft … and had the effect of depriving Starkey of a significant tax benefit of more than $14 million, which our [Northland Hearing] subsidiary could have claimed as a future deduction.”

The scheme resulted in Starkey paying more in taxes than it owed, Austin said.

The allegations add to a list of charges that accuse Ruzicka, Nelson and Larry Miller, the fired head of human resources for Starkey, of fraud, embezzlement and conspiracy to commit money laundering.

Two colleagues of Ruzicka and Nelson who did not work for Starkey also are charged.