Orlando Shooter Sent Wife Text Messages During Massacre, Sources Say

— -- Orlando shooter Omar Mateen sent text messages to his wife Noor Mateen during the massacre at Pulse nightclub and a grand jury investigation is underway in the case, sources briefed on the investigation told ABC News.

It remains unclear whether Noor Mateen was aware of the carnage her husband was inflicting on club-goers at the Pulse nightclub on June 12 when she received the messages. It was unclear what the messages said and it was also unclear what, if anything, she knew about the attack before it was perpetrated.

Orlando Nightclub Massacre

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In the early morning hours of Sunday, June 12, 2016, a man entered the Pulse, a gay nightclub in Orlando, Fla., and perpetrated the deadliest mass shooting in U.S. history, resulting in the deaths of 49 people and injuring at least 53 others.<br><br>Orlando Police officers direct family members away from a multiple shooting at a nightclub in Orlando, Fla., June 12, 2016.

AP Photo/Phelan M. Ebenhack

Noor Mateen, 30, was interviewed by the FBI for the first time on June 12 in Fort Pierce, Florida, located about two hours southeast of Orlando.

A law enforcement official previously told ABC News that she may have known something about the massacre in advance but claims she tried to talk him out of the assault.

Officials are trying to assess the veracity of that claim.

Noor Mateen was with her husband when he recently bought ammunition and a holster, sources familiar with the investigation told ABC News. The couple had also recently gone to the Disney World area together, though authorities are unclear if it was a family trip or if Mateen was there to case a possible target, the sources said.

The FBI has obtained subpoenas for financial records, which means that there is now a grand jury investigation. However, sources tell ABC News this grand jury is not looking at Noor Mateen specifically. Rather, it was previously impaneled, and for the moment, is being used only as an investigative tool.

Both the shooter's wife and Mateen's father Seddique, have been placed on no-fly lists by federal officials, as they remain under scrutiny.