WALTHAM — The night before Thanksgiving, Emerson Antonio Aroche Paz was walking down the street around 10 p.m. when he saw someone heading toward him in the rain. He moved over to give him room to pass and when they were almost shoulder to shoulder heard him take a deep breath. Then, without warning, the man hit him in the head twice, sending him reeling into the road.
He “hit me in my left eye,” Aroche Paz, 41, said in an interview Tuesday. “It happened very quickly.”
Aroche Paz is among at least 10 men who were targeted here in recent weeks, in a string of random, brutal street attacks that have frustrated investigators and set residents on edge.
“There is definitely a fear factor in our city right now,” said Waltham Police Detective Sergeant Steve McCarthy. “We’ve never experienced anything like this.”
On Tuesday, city officials announced a $5,000 reward for information leading to the arrest and conviction of the person responsible for the unprovoked attacks, which began Nov. 10. The man appears to lie in wait for unsuspecting victims, sneaking up from behind and viciously assaulting them. He flees quickly on foot, without stealing anything.
“The motive is somewhat in question but it appears to be a thrill of the assault, or someone who’s very violent and enjoys seeing someone hurt by this,” Police Chief Keith MacPherson said at a news conference. “There’s never been a robbery; it’s always been just an assault and the assailant takes off.”
Over the weekend, police released video footage of a man they identified as a suspect, whom multiple victims have described as a Black man between 5 foot 5 inches and 6 feet tall wearing a mask or a hoodie tied tightly around his face. Investigators implored pedestrians to be cautious and alert the authorities if they see anything suspicious.
“We are once again urging residents to be aware of their surroundings, particularly when they are out after dark,” MacPherson said. Multiple people could be responsible for the attacks, police said.
The attacks began near the Gardencrest apartment complex but have since extended to the city’s downtown. The most recent attack occurred the day after Thanksgiving.
The victims have all been men, the youngest 20 and the oldest in his mid-to-late 40s. Police believe the attacker is armed with a weapon.
“They’re pretty serious injuries, including orbital facial fractures, fractured nose, lacerations to the face,” he said. “So we don’t believe it can be just someone’s fist.”
Aroche Paz said he lost his balance as a result of the blow, but didn’t fall to the ground. But before he had a chance to react or defend himself, the man struck him again in the back of the head.
Bleeding, Aroche Paz stumbled into the middle of the street. He wiped the blood from his face so he could see his assailant, but the man had already fled.
“I don’t know where he went,” Aroche Paz said.
He looked down at his phone, which was covered in blood, and started walking toward a gas station. He called 911. He then told police about his ordeal.
Aroche Paz said he was released from the hospital at around 5 a.m. on Thanksgiving Day.
“My nose broke. Part of my head is cracked,” he said. “But my brain is fine.”
Aroche Paz, who is 5 foot 10, said his attacker was about his height and had his face covered. He said he worries the man could strike again and hopes police in surrounding communities are on alert.
“I was not prepared for this,” Aroche Paz said.
The random nature of the attacks, against victims who were seriously injured but not robbed, suggests a number of possibilities, said James Alan Fox, a professor of criminology, law, and public policy at Northeastern University.
The attacker could be motivated by the “thrill” of hurting his victims and avoiding apprehension, he said.
“It makes them feel powerful, dominant,” Fox said. “They are enjoying the experience of beating people and getting away with it.”
Such attacks are difficult to understand because there’s no obvious motive, like revenge or money. But the feeling of power and invincibility gives the assailant gratification.
Fox said it was similar to incidents across the country where people have randomly shot at passing cars, only more intimate since these attacks were carried out up close.
The attacker may suffer from mental illness, Fox said. But such crimes tend to be spontaneous and committed by someone who was not necessarily aware of the risks or the possibility of being identified by witnesses. In this case, it appeared the attacker was waiting for his victims.
“Someone who is lying in wait is being strategic about it,” Fox said. “It would tend to suggest the thrill aspect as opposed to mental illness.”
In Waltham, police have stepped up patrols and are using drones for surveillance. Police contacted the Boston Police Department’s gang unit to see if they had received reports of any similar attacks as initiation rituals, but they hadn’t.
Waltham Mayor Jeannette McCarthy said residents are understandably alarmed.
“You just worry for everybody,” she said. “It could be your kids, it could be your brother, could be a family member. These people are regular people, they’re just walking, and they’re getting hurt, very badly hurt.”
Residents at the Gardencrest apartment complex, where several of the attacks occurred, said their nerves were frayed.
“So I just saw here the mayor said, ‘Oh, don’t go out after dark,’ and I’m going, COVID’s bad enough,” said resident Donna Johns, 72. “We’re stuck in the house, we can’t be places we’d like to go. . . . And now I can’t go out after dark. Is the mayor going to come walk my dog with me? So I’m annoyed. I’m angry. I’m anxious.”
Lori LeDuc-Smith, 50, said she plans to move when her lease ends.
“This is like a nail in a coffin that was already pretty much sealed,” she said. “With what’s going on, I’m scared. My mom’s texting me, neighbors on the other side of town are texting me, making sure that I know and that I’m careful.”
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