Employees of Advanced Granite Solutions at the shooting site Wednesday. (Sarah L. Voisin/The Washington Post)

Jose Hidalgo Romero, one of five people who were shot Wednesday in a Maryland workplace attack allegedly carried out by a fellow employee, had complained to his boss about abusive behavior by the co-worker long before the shooting, but no action was taken because the suspect was deemed to be "a good worker," according to Romero's brother.

"He knew something was going to happen," Noel Orellana said of Romero, one of three employees killed in the shooting at Advanced Granite Solutions, a countertop company in Edgewood, Md., about 40 miles northeast of Baltimore.

In an interview Thursday, Orellana said that Romero, 34, had been looking for a new job for several weeks because he was afraid of the co-worker, identified by authorities as Radee Labeeb Prince, 37, who was arrested Wednesday after a day-long manhunt.

After the Maryland shooting, Prince allegedly drove 50 miles to Wilmington, Del., where he lived, and shot a sixth person, also an acquaintance, in the head and body. That victim survived the attack, which occurred at a used-car dealership.

Orellana quoted his brother as saying that Prince would punch people in the back and start fights at Advanced Granite and that employees met with an owner of the company to complain about the problem. According to Orellana, Romero said that the owner's response was, "Leave him alone — he's a good worker."

Ron Cherry, a lawyer for Advanced Granite, which employs about 35 people, declined to comment on Orellana's allegations, citing the continuing police investigation into the circumstances that led to the violence. Two wounded employees who survived the shooting remained hospitalized Thursday in critical condition.

Radee Labeeb Prince was held Thursday in Delaware for attempted murder as part of a set of shootings Wednesday in which police say he killed three co-workers in Maryland. (Courtesy of Maryland State Police/Courtesy of Maryland State Police)

"Words cannot express our shock and sadness," Cherry said. "We are a small business, and we know each of these victims intimately."

In a Wilmington courtroom Thursday, Prince pleaded not guilty to four charges related to the shooting in that city, including attempted murder. His bail was set at $2.1 million. He has not yet appeared in court in Maryland, where the Harford County sheriff said he has been charged with murder.

Meanwhile on Thursday, new details emerged about the terror that unfolded inside Advanced Granite when about 10 employees, gathered in a semicircle around Prince, suddenly came under close-range gunfire, authorities said.

In an interview, Harford Sheriff Jeffrey R. Gahler said surveillance video shows Prince shortly before 9 a.m., standing in the company's workshop with about 10 of the 29 people who were working that day.

Prince called the employees to gather around him, Gahler said.

"The suspect does bring the victims together, and as they come close, he pulls out the handgun and begins shooting," the sheriff said.

One of the dead was Romero, who has a wife and two children in El Salvador, according to his brother. The family is trying to arrange to ship his body there.

"He was a very humble guy," Orellana said. "Our hearts are broken."

Authorities identified the other slain employees as Enis Mrvoljak, 48, of Dundalk, Md., and Bayarsaukhan Tudev, 53, whose last known address was in Virginia.

Gahler said investigators are aware of complaints about Prince at Advanced Granite, where he had worked for about four months, and at past jobs. "There were some concerns about some of his behavior, and at other workplaces some assaults had taken place," the sheriff said. "There seems to be a history with this individual of workplace violence."

In February, for example, the owner of another countertop company in Harford County filed a court petition, asking a judge to order Prince to stay away from him.

"I fired him for punching another employee on the face," the owner said in his petition, which was denied for lack of evidence. He wrote that Prince — "a big guy and very aggressive on me" — had harassed him several times after being fired. "He did not hurt me physically," the owner wrote, "but I do not want to wait 'till he will."

More details also surfaced Thursday about the Wilmington attack, with court documents describing a violent encounter between Prince and the victim early last year.

Family members identified the victim as Jason Baul, 35, who owns Baul's Auto Sales, where the shooting occurred. In January 2016, Baul reported that Prince had assaulted him in a robbery attempt at the home of an acquaintance, according to a court affidavit filed by a police officer. "Radee grabbed him and started punching him," the officer wrote, and "kept reaching into his waistband," as if he had a gun.

Prince was charged with assault and other crimes, but the case was thrown out, according to court records. Prince later filed a lawsuit against Baul over the incident, and the civil case remains unresolved in a Delaware court.

"Our family has been friends with their family since I can remember, since we were walking," said Robert Baul, 37, of Atlanta, a brother of Jason Baul's, speaking of Prince. "We grew up together."

Employees of Advanced Granite, which is temporarily closed, gathered outside the building early Thursday afternoon, hugging one another on the sidewalk.

Stefanie Shedy, 30, an accountant who left the company more than a year ago, said she still felt close to her former co-workers. She stopped by to leave flowers at a small memorial site in the parking lot.

"They're like a tightknit family, this company," Shedy said. "I can't understand why anyone would want to hurt them." She said the owners are "very good to their employees," including helping them with financial and housing issues.

She knew four of the victims, all longtime employees, and said they were "very fun and carefree, always smiling." She said she did not know Prince.

An intensive search for Prince on Wednesday, involving numerous police officers in the Mid-Atlantic region as well as federal agents, ended at 7:05 p.m. in Newark, Del., where Prince was arrested, Wilmington Police Chief Robert Tracy said.

After a day of media coverage, with photos of Prince appearing on numerous websites and TV stations, tipsters called authorities in the early evening to report seeing the suspect and his vehicle, a 2008 GMC Acadia, in a Newark neighborhood about 20 miles southwest of Wilmington. Two federal agents arrested him there after a foot chase, during which Prince tossed away a .380-caliber handgun, authorities said.

The weapon was being tested to determine whether it was used in the shootings.

Lynh Bui and Dan Morse contributed to this report.