The chairman of the House science committee announced Wednesday he is issuing a subpoena to the Environmental Protection Agency for information related to the potential deletion of roughly 5,000 text messages from Administrator Gina McCarthy's phone.

Rep. Lamar Smith, R-Texas, chairman of the Committee on Science, Space and Technology, made the original request in January, following news reports that messages may have been accidentally or perhaps improperly deleted from McCarthy’s government-issued cell phone.

He says the agency has partially complied with the inquiry, which includes sending redacted documents. But, in a letter obtained by FoxNews.com, Smith tells McCarthy he is forced to issue the subpoena after the EPA stopped responding to additional committee emails, letters, calls and closed-door briefing requests.

“Because EPA has refused to provide a complete production of records to the committee’s repeated requests, I am left with no alternative but to issue a subpoena,” he wrote McCarthy in the letter. Smith is specifically seeking phone bills, emails and other documents. 

The subpoena comes several weeks after revelations that Hillary Clinton, as secretary of state, used a personal email server and at least one personal email account for official correspondence. 

The EPA publicly has said McCarthy’s lost or deleted texts are not subject to disclosure and such messages can be legally deleted. The agency did not immediately return a request for comment. 

Beyond the concerns over those assertions, Smith and other committee members are also concerned about the EPA saying Friday that the request for McCarthy’s cellphone records was being delayed so the agency could redact numbers associated with her friends.

“Excluding phone numbers of ‘friends’ raises serious concerns and is insufficient for the committee’s oversight purposes,” Smith wrote in the letter. 

The subpoena follows another EPA incident that called into question the agency's transparency. 

McCarthy’s predecessor, Lisa Jackson, used the email alias “Richard Windsor” to conduct official business. The agency has said Jackson used the alias because her official address was publicly known, jamming her account with an overloaded inbox.

Another major red flag is the EPA’s claim that McCarthy received only one text message -- since she became administrator in 2013 -- that qualifies as a federal record.

The email was sent in early February by long-time supporter and President of the League of Conservation Voters Gene Karpinski, praising McCarthy’s comments in apparent opposition to the completion of the Keystone XL oil pipeline.

McCarthy requested her assistant preserve the email, just days after it was received and after the committee’s request.

“EPA would have the committee believe that of the more than 5,000 texts sent or received by you on your agency phone, the only one that was related to official business and required consideration for archiving was received less than 10 days after the committee wrote to the agency requesting information about your text messages and archiving practices?” the letter asked.