U.S. officials will release partial transcripts of three phone conversations that the gunman who killed 49 people in a Florida gay club had with law enforcement during the massacre, Attorney General

The now-deceased gunman, Omar Mateen, paused during his three-hour siege at the club in Orlando last Sunday to call emergency 911 dispatchers and post internet messages professing support for Islamist militant groups, authorities have said.

The rampage, the deadliest mass shooting in modern U.S. history, has triggered a week of national mourning and soul-searching over the easy accessibility of firearms and the treatment of gay, lesbian, bisexual and transgender people.

Speaking on CNN's "State of the Union" program, Lynch said the partial transcripts of Mateen's calls from the Pulse nightclub would be released on Monday and include the "substance of his conversations."

She later told ABC's "This Week" that the transcripts would not include Mateen's pledge of allegiance to Islamic State, the militant group that has urged its followers to attack targets in Europe and the United States.

Lynch said the investigation was focused on building a complete profile of Mateen, a 29-year-old U.S. citizen born to Afghan immigrants, including what motivated him, in order to prevent another Orlando massacre.

Authorities believe Mateen was "self-radicalized" and acted without any direction from outside networks.

Lynch, who will travel to the central Florida city on Tuesday to confer with investigators and meet survivors and victims' loved ones, declined to say whether a federal grand jury was likely to charge Mateen's second wife, Noor Salman, or anyone else.

U.S. officials have said Salman knew of her husband's plans to carry out the attack.

"Because this investigation is open and ongoing, we're not commenting on anyone else's role in it right now, except to say that we are talking to everyone who knew him, and that of course includes his family, to determine what they knew, what they saw in the days and weeks leading up to this," Lynch said.

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She noted that the transcripts would be redacted to avoid causing further pain to Mateen's victims and their loved ones.

The attorney general's remarks came ahead of a vigil Sunday evening at a lakeside park in Orlando. More than 20,000 people are expected to attend, city officials said.