Mourners Ronny Torres, right, is comforted by Zaid Hinds at a memorial in Orlando, Fla. Hinds and Torres lost 12 friends in the shooting. (AP Photo/David Goldman)

ORLANDO — Investigations into the Orlando nightclub massacre ranged from a German bank to a quiet town north of San Francisco on Wednesday, with the gunman’s family coming under increasing scrutiny in the struggle to understand the motives and planning for the deadliest mass shooting in U.S. history.

Since Sunday’s attack, authorities have confronted a jumble of potential leads and loose ends, including why an earlier FBI investigation into the gunman was closed and whether Sunday’s slaughter at the gay-oriented club was an act of politically driven rage or triggered by personal demons — or even a mix of both.

Without an apparent self-written manifesto or video message by the 29-year-old shooter, Omar Mateen, investigators have looked for clues among survivors and former friends to dig into his psyche. They also have looked deeper into his family — particularly his wife — for any possible knowledge of Mateen’s plans before the bloodshed.

Three people identifying themselves as FBI agents conducted interviews Tuesday in the neighborhood in northern California where Mateen’s wife was raised in a family with Palestinian roots, the Associated Press reported. In separate questioning, Noor Zahi Salman told the FBI that she accompanied Mateen on at least one trip to the Orlando club Pulse before the attack for what a U.S. law enforcement official described as “reconnaissance.”

[Survivor’s tale: “The guilt of being alive.”]

Salman, 30, has not been placed under arrest, but she has emerged as a possible critical link in the struggle to understand Mateen — a security guard and bodybuilder — and what caused him to storm the crowded club and leave 49 people dead before being killed by police.

Meanwhile, German investigators examined a Düesseldorf bank account held by Mateen’s father, who has claimed that his son visited the day before the attack and showed no hints of anger or anxiety. Germany’s Rheinischen Post reported that Mateen’s Afghanistan-born father, Seddique Mateen, posted the bank account details in a 2013 video soliciting donations — receiving only two payments totaling the equivalent of about $200.

There was no immediate indication of how the money was used, but the elder Mateen has been active in the Afghan expatriate community in the United States and elsewhere as a self-proclaimed political figure and analyst.

As the survivors of the attack recount their stories of raw terror, some possible nuggets have emerged for investigators.

Mateen, 29, said he carried out the attack because he wanted “Americans to stop bombing his country,” according to a witness who survived the rampage and heard the shooter make a 911 call — in which he proclaimed loyalty to the Islamic State but also mentioned other Islamist militant factions and the 2013 Boston Marathon bombing.

Mateen made at least one other phone call during the standoff, to an acquaintance he knew from in Florida, two U.S. law enforcement officials said. It’s unknown what Mateen told this person. Mateen’s phone has been recovered and forensic experts were about to access the data, an official said.

President Obama said Tuesday that the gunman “was an angry, disturbed, unstable young man who became radicalized.”

Obama, speaking after a meeting with his National Security Council, also said that the investigation has not turned up any suggestions that the gunman was directed by a foreign terrorist organization.

[FBI faces questions after dropping earlier probe into Orlando gunman]

“It is increasingly clear, however, that the killer took in extremist information and propaganda over the Internet,” said Obama, who plans to travel Thursday to Orlando. Obama said that the Islamic State, a militant group also known as ISIS or ISIL, has made its propaganda “pervasive and easily accessible” and that it appeared the shooter in Orlando “absorbed some of that.”

Vice President Biden, speaking at an event in New York, suggested Tuesday that the investigation had shown that the incident was “more straightforward” than it initially appeared.

“We are getting to the bottom of this, and it’s becoming clearer and more straightforward than a lot of us even thought,” said Biden, who attended a national security meeting before the event. He did not elaborate.

The FBI has said it was also exploring whether anti-gay bigotry prompted the attack on the popular gay nightclub. Adding another dimension to the probe, at least two witnesses at Pulse said Mateen had previously visited the club. They also said they had seen him on Jack’d, a dating app for gay men.

The bureau was also facing questions over whether it missed warning signs during a 10-month probe of the shooter that ended two years before the massacre. During that investigation, the gunman had been placed on a terrorism watch list. His wife, Salman, had apparently never come to the attention of the FBI.

The first U.S law enforcement official said the wife warned Mateen not to carry out the attack, apparently as he was leaving Saturday night for Orlando. The official said the couple visited the club between June 5 and June 9. FBI officials said Mateen bought the guns in early June.

Salman has made no public statements, but a portrait of a shy and sheltered woman has emerged from former neighbors in her hometown of Rodeo, Calif., an area of oil refineries and rolling hills about 25 miles northeast of San Francisco.

[Republicans turn on Trump over Orlando reaction]

Her romance with Mateen began online — as with her first husband — and they were married on Sept. 29, 2011, in an Islamic ceremony in Hercules, Calif., a town near Rodeo, according to friends and public records. The couple has a 3-year-old son.

Jasbinder Chahal, who has lived across the street from Salman’s childhood home for the last 15 years, told the AP that Salman did not appear to have lofty ambitions beyond marriage after graduating from high school in 2004.

“You know, some kids after high school, they open up the box and the world is theirs,” Chahal said. “She was inside the box, just pack it up and get married.”

He added: “Noor never played in the street, and the girls were never allowed to drive.”

The FBI investigated Mateen beginning in 2013, putting him under surveillance, recording his calls and using confidential informants to gauge whether he had been radicalized after the suspect talked at work about his connections with al-Qaeda and dying as a martyr.

It was during this probe, which ended in 2014, that Mateen was placed on a terrorism watch list. After the FBI closed its preliminary investigation into Mateen in 2014, his name emerged months later in a separate probe, this one looking into a Florida man who became the first American suicide bomber in Syria. Investigators said they did not find any significant ties between the two men, who attended the same mosque in Fort Pierce, Fla.

The night of the shooting, Patience Carter, 20, said she heard the gunman explain his motives during a 911 call in which he also pledged allegiance to the leader of the Islamic State.

At one point, while Carter was in the club bathroom with several other hostages, she said the gunman asked if there were any black people in the room. When one man said yes, the shooter said, “You know I don’t have a problem with black people,” Carter recalled during a news conference. “This is about my country,” Mateen said. “You guys suffered enough.”

Mateen’s claim that he carried out the shooting to “stop bombing” echoed a message Boston Marathon bomber Dzhokhar Tsarnaev scrawled in a note before he was taken into custody by police. Tsarnaev, who was sentenced to death last year, wrote that the U.S. government was “killing our innocent civilians” and that as a Muslim, “I can’t stand to see such evil go unpunished.”

Even though Mateen was born in New York, the shooting has fueled a resurgent debate on U.S. immigration policy. Republican presidential candidate Donald Trump called Monday for barring immigrants from areas of the world with a history of terrorism as part of a proposed temporary ban on Muslims entering the United States.

During his remarks Tuesday afternoon, Obama dismissed the suggestion from Trump and others that he use the phrase “radical Islam” when discussing attacks.

“What exactly would using this label accomplish?” Obama asked. “What exactly would it change? Would it make ISIL less committed to trying to kill Americans? Would it bring in more allies? Is there a military strategy that is served by this? The answer is, none of the above. Calling a threat by a different name does not make it go away. This is a political distraction.”

Goldman and Murphy reported from Washington. Julie Tate, Mark Berman, David Nakamura and Missy Ryan in Washington and Zachary Fagenson in Port St. Lucie, Fla., contributed to this report.