Buried in a sea of disturbing videos that Frank R. James posted on YouTube in recent weeks was a plan.
In between bigoted screeds tied to current events, he described an itinerary that would take him on a trip from Milwaukee in late March to the East Coast, where he was born. In more than one video, he recorded himself behind the wheel of a rented van, apparently making that journey back to what he called “the danger zone.”
And the day before the attack in which the police say he opened fire on a subway car, shooting 10 people and injuring at least 13 more, Mr. James posted a video in which he said he had often wanted to kill and to “watch people die”right in front of him.
The thought of prison restrained him, he said, adding: “It’s important to think about what you’re going to do before you do it.”
Mr. James was arrested on Wednesday and charged with committing the worst crime on New York’s subway system in nearly 40 years. Investigators and the broader public were still struggling to piece together what made him tick — and how the hours of footage he posted offered a hidden preview of an attack he may have been planning for weeks.
In a sense, Mr. James’s travel eastward retraced the steps he had taken earlier in life. He was raised in the Bronx but mostly lost touch with his family as he grew older, his sister said. He drifted south and then west, to Newark, then Philadelphia, then Chicago — arrested many times but never convicted of anything serious enough to prevent him from buying a handgun, which he did in Columbus, Ohio, in 2011.
He landed in Milwaukee, where neighbors in his most recent home described him as a sullen, irascible loner. But there, apparently alone in his apartment, he built himself a YouTube personality. Referring to himself as the “prophet of doom,” he posted thoughts on race and global affairs and, eventually, threats of violence that, in at least one video, he imagined taking place in New York’s subway system.
“He can’t stop no crime in no subways,” Mr. James said of New York City’s mayor, Eric Adams, in one video. “He may slow it down but he ain’t stopping it.”
He added: “That means you’d have to have police in every station and that’s just not possible.”
Mr. James was born in 1959 — in Manhattan, according to public records, but in the Bronx, according to his sister Catherine James Robinson. Their mother died when Mr. James was 5, and his relationship with other family members frayed as he grew older, Ms. Robinson said.
“He’s been on his own all his life, and I haven’t had that much contact with him,” she said. “He moves from city to city.”
One of the last of those cities was Milwaukee, where it was unclear what Mr. James did for work. He described himself as a driver, including for the delivery app Instacart. (Instacart did not reply to several requests for comment.)
He seems to have been more focused on his YouTube account, where the videos he posted frequently devolved into outbursts of homophobia, misogyny and offensive comments about Black people, Hispanic people and white people. Mr. James, who is Black, directed much of his hatred toward Black people, whom he often blamed for the way they were treated in the United States.
He expressed admiration for Black trailblazers like Martin Luther King Jr. and President Barack Obama but unleashed vitriol on other Black people, including Daunte Wright, who was killed by a police officer in Minnesota last year, and other young Black men shot by the police. He blamed them for their own deaths, saying, “You play stupid games, you win a stupid prize,” and adding that they deserved to be shot.
Current and former neighbors in Wisconsin described him as gruff, standoffish and prone to losing his temper. Keilah Miller, who lived in an adjacent unit to Mr. James in Milwaukee, said he had blown up at her after she had left her key in her lock, yelling, “Don’t ever do that again!” She said he had few visitors.
A former neighbor, Mike Lopez, 38, said he never spoke to Mr. James but often saw him pushing a small cart with groceries or other possessions.
“I didn’t see him as no threat or nothing,” Mr. Lopez said before the arrest. “I mean, I don’t see him as capable as that. He can’t move like that, man. He wasn’t fast.” Mr. James’s sister also mentioned his physical difficulties, saying that he had a bad back and was not easily able to get up and down stairs.
He was kinder to his YouTube audience than to his neighbors. Even after his angriest videos — like the one that comments on Mr. Wright — he signed off in a friendly manner, telling his audience to “take it easy.” On March 21, he noted with some distress, “My numbers have been going down on YouTube here recently, maybe over the last couple of days,” before declaring himself unbothered.
Ms. Miller said on Tuesday that she had not seen Mr. James since late March — a timeline that aligns with Mr. James’s description of his recent travels.
In a video posted on March 18, Mr. James said he picked up a Penske van and was planning to leave Milwaukee the following day. Two days later, shooting a video from the road, he explained that he had packed up his apartment, emptied his storage unit and set out early on a trip to Philadelphia, where he was planning to move.
Filming himself from the rented van, he said he was struggling with his emotions.
“On the drive I’m just thinking because I’m heading back into the danger zone, so to speak, and it’s triggering a lot of negative thoughts, of course, because I do suffer from — have a bad case of post-traumatic stress from all the things I’ve been through,” he said in the video.
He stopped for the night in Fort Wayne, Ind., and said he would stop in a town outside of Pittsburgh next, then Harrisburg, Pa., and Philadelphia, which he would reach by Tuesday.
Mr. James said in that video that he planned to spend six days in a hotel and then transfer to a short-term rental.
Once in Philadelphia, Mr. James said he was driving to a storage locker facility to store his belongings. He then gave a brief video tour of a hotel room in New Jersey. “All my troubles started in the state of stinking New Jersey,” he said, using an expletive.
There was truth to that aside: Police officials said that Mr. James was arrested three times in New Jersey, the first time in 1991, the most recent in 2007. He was arrested nine times in New York from 1992 to 1998 and was charged with possession of burglary tools, criminal sex act and criminal tampering.
Mr. James faced two charges for making terroristic threats in New Jersey in the mid-1990s. But he was found guilty of harassment, a lesser charge, and sentenced to probation and counseling.
In his videos, Mr. James ranted against counseling programs that he said were supposed to make him feel better but wound up making him worse off. He directed much of his ire toward workers at the South Bronx Mental Health Council, though it remains unclear when he began counseling or why. Court documents suggested that he was already enrolled in a different program in 1997 in New Jersey at the time he was convicted.
In Philadelphia, by his own account, Mr. James was having some housing trouble. In a video posted March 27, he said that a heater had broken where he was staying and that he had to move to another room.
The following day, he began his stay at a property owned by Janet McDaniel, 74, a former caseworker for the Pennsylvania State Department of Public Welfare who manages several short-term rental properties. Mr. James booked the stay through Evolve, a short-term rental platform.
Ms. McDaniel said that Mr. James had originally been scheduled to leave the duplex — situated near the corner of a block in Philadelphia’s Nicetown neighborhood, not far from Temple University Hospital and the medical school campus — on April 10 but appeared to have extended his stay until April 15.
She had little contact with him — he called her once to tell her that the cable wasn’t working — and entered the apartment Tuesday, expecting him to have left, and was surprised to find a number of belongings still there, including a nearly empty suitcase and a pair of scissors. Food had been left in the refrigerator, clothes were hanging in the closet and the television was blaring.
“At that time, I decided let me get out of here,” Ms. McDaniel said.
The same morning, federal agents swooped into the property. In searches of multiple properties associated with Mr. James in Pennsylvania, law enforcement officers were able to find ammunition for a 9-millimeter handgun as well as a barrel that would allow for the use of a silencer, and ammunition that can be used in an AR-15 rifle.
As a short-term tenant, neighbors said, Mr. James had kept to himself, so much sothat he seemed more like a construction or maintenance worker rather than a tenant.
Ayana McKay noticed Mr. James during his two weeks at the property but rarely interacted with him, she said. Ms. McKay, 23, was home when federal agents barged in on Tuesday morning, pointing guns at her and demanding to know whether she was a hostage or was hiding anyone in her apartment.
At that point, Mr. James was in New York, perhaps hewing to a different travel plan. Though in one video he mentioned that he planned to leave the rental this Friday, he said in another that he would only stay for about 15 days, exactly the amount of time that passed between his booking of the rental and the day of the shooting.
Dan Simmons contributed reporting. Susan C. Beachy and Kitty Bennett contributed research.