Kevin Johnson

USA TODAY

The popular Orlando gay nightclub where Omar Mateen carried out the deadliest mass shooting in U.S. history was the gunman's only target in an assault that was described Wednesday by the FBI's lead investigator as both a crime of hate and terrorism.

While federal authorities have been reviewing whether the 29-year-old security guard had considered other locations in the area, including Disney World, Ron Hopper, who is managing the broad federal inquiry, said there was no evidence to indicate other possible targets.

Much of the investigation so far has focused on Mateen's activities in the days before the massacre, primarily an account provided by the gunman's wife who allegedly told authorities that she sought to dissuade Mateen from launching an attack on the club. A federal law enforcement official who is familiar with the matter but not authorized to speak publicly has said that Noor Salman, 30, also told agents that she drove Mateen to the Pulse nightclub at least once before her husband launched the attack.

Orlando nightclub shooting: What we know Wednesday

The official said authorities were weighing whether Salman's knowledge was detailed enough to have alerted law enforcement to the plot, which could expose her to possible criminal prosecution. But Hopper said Wednesday that there were "no impending charges.''

"With respect to the wife,'' Hopper said, "that is only one of many interviews that we have done.''

Orlando U.S. Attorney Lee Bentley III also suggested that a decision on charges was not imminent.

"Indeed, we don't know what charges will be brought, or if charges will be brought,'' Bentley said.

Hopper said much work remains at the pock-marked crime scene where investigators continued to reconstruct how the assault unfolded during the early morning hours Sunday.

"It is imperative that we get this right,'' he said.

A federal law enforcement official familiar with the ballistics analysis said investigators are in the midst of an enormous task of gathering and identifying shell casings left by the gunman and at least 11 officers who engaged Mateen at one time or another during a gun battle that ultimately ended in Mateen's death.

Orlando shooting at Pulse nightclub

It could take days to complete a full accounting of the rounds expended by the gunman and officers both inside and outside of the nightclub, said the official, who is not authorized to comment publicly.

Earlier Wednesday, Siddique Mateen, the gunman's father, met with reporters outside his Port St. Lucie, Fla., home where he offered both an apology for his son's actions and a belief that the radical influences of the Islamic State, also known as ISIS or ISIL, had apparently overtaken his son without his knowledge.

"ISIS is the most dangerous group on the face of the earth,'' he said. In addition to the Islamic State, the gunman also pledged his solidarity with the Boston Marathon bombers and an American-born suicide bomber who died in a 2014 attack in Syria.

As recently as Monday, FBI Director James Comey said it was "not entirely clear'' what terror interest the gunman sought to support.

The father, in an often-rambling appearance, also suggested that the club's security system was inadequate, once referring to it as "sloppy.''

Though he pledged to cooperate with investigators, he said no other members of his family are "involved in this.''

He did not answer specific questions about his daughter-in-law's possible knowledge of the plot, except to describe her as the "most sincere, most wonderful lady that I have known.''