WASHINGTONWASHINGTON (Reuters) - The U.S. State Department will do everything necessary to determine whether former U.S. ambassador Marie Yovanovitch was under threat in Ukraine, Secretary of State Mike Pompeo said on Friday.

Documents released this week indicated Lev Parnas, a Ukraine-born U.S. citizen, helped U.S. President Donald Trump's personal lawyer Rudy Giuliani investigate U.S. presidential candidate Joe Biden and his son Hunter.

They also showed Parnas was involved in monitoring Yovanovitch's movements before Trump removed her in May. Yovanovitch, a respected career diplomat, was a key witness in the U.S. House of Representatives' investigation of Trump before he was impeached in December.

ADVERTISEMENT

Late on Friday, a Democratic aide said House Democrats will be sending additional text messages, photographs and other documents provided by Parnas for the Senate impeachment trial that gets underway in earnest next week.

Some of the documents appeared to show communications between Parnas and an aide to Representative Devin Nunes, the senior Republican on the House Intelligence Committee.

In his first comments on the issue since the documents were released on Tuesday evening, Pompeo said he had never met nor communicated with Parnas, adding that he thought much of what had been reported on the issue would be proven wrong.

"We will do everything we need to do to evaluate whether there was something that took place there," he told conservative radio host Tony Katz in an interview.

"I suspect that much of what’s been reported will ultimately prove wrong, but our obligation, my obligation as secretary of state, is to make sure that we evaluate, investigate. Any time there is someone who posits that there may have been a risk to one of our officers, we’ll obviously do that," he said.

Yovanovitch testified she had received a late night call from Washington warning her that she needed to return to the United States urgently and that there were concerns about her safety.

ADVERTISEMENT

"NO HARM"

Her potentially illegal surveillance could be an important element of the impeachment trial on whether to remove Trump from office that formally began on Thursday.

Trump is charged with abusing his power and obstructing Congress for pressuring Ukraine to investigate former Vice President Joe Biden, a Democratic political rival. Trump denies wrongdoing.

The documents released on Tuesday included encrypted messages between Parnas, a Florida businessman, and Robert F. Hyde, a Republican congressional candidate in Connecticut, disparaging Yovanovitch and apparently providing updates on her movements in Kiev.

"It is always the case at the Department of State that we do everything we can to ensure that our officers, not only our ambassadors but our entire team, has the security level that’s appropriate," Pompeo said.

"We do our best to make sure that no harm will come to anyone, whether that was what was going on in our embassy in Baghdad last week or the work that was going on in Kyiv up and through the spring of last year when Ambassador Yovanovitch was there, and in our embassy in Kyiv even today," he added.

ADVERTISEMENT

The Ukrainian Interior Ministry on Thursday also announced an investigation into the possible illegal surveillance of Yovanovitch. House prosecutors may call Parnas if the Senate permits testimony in the trial.