The House ethics committee is expanding its investigation of Ways and Means Chairman Charlie Rangel (D-N.Y.) to include his August disclosure of more than $500,000 worth of assets that he failed to previously report.

The Committee on Standards of Official Conduct has been investigating Rangel for months over an array of failures in his financial reporting, including his failure to report rental income from a Dominican beach house.

Rangel last year announced that he was hiring a forensic auditor to review all of his disclosure forms and make the appropriate amendments. He also asked the ethics committee to commence the investigation into his finances, saying he was confident the committee would find no wrongdoing.

In August, Rangel filed amended disclosure forms for 2007 and prior years that added about a dozen assets worth more than $500,000 that he had not previously disclosed.

The ethics committee announced Thursday that it voted unanimously to expand the charge of the subcommittee investigating Rangel “to determine if Representative Rangel violated the Code of Conduct or any law, rule, regulation or other standard of conduct … with respect to all Financial Disclosure Statements and all amendments filed in calendar year 2009.—

The committee said that, thus far in the investigation, the subcommittee has “authorized the issuance of close to 150 subpoenas; interviews approximately 34 witnesses resulting in over 2,100 pages of transcripts; reviewed and analyzed over 12,000 pages of documents; and held over 30 investigative subcommittee meetings.—

Republicans have argued that Rangel should be forced to relinquish his gavel while the investigation continues.