Mass shooting in Rock Hill, South Carolina
On April 7, 2021, six people were shot and killed at a house in Rock Hill, South Carolina by Phillip Adams, a former reserve cornerback in the National Football League. Adams, who lived in Rock Hill, killed four of his neighbors (a couple and their two grandchildren in the Lesslie family) at their home, as well as two repairmen who were working on the house's HVAC unit. After leaving the scene, he went to his parents' house, where he was found by police. The police tried to negotiate with him, but he fatally shot himself, and was found dead the next day. 
Adams' motive was never discovered. However, in his autopsy, he was diagnosed to have had a Stage II case of chronic traumatic encephalopathy (CTE), a brain disease which he likely received from damage to his frontal lobes while playing football. This included two concussions he received while playing for the Oakland Raiders in 2012. CTE is caused by repeated injuries to the head and can lead to cognitive decline; damage to the frontal lobes can result in violent and impulsive behavior.
Background.
Perpetrator.
Phillip Adams was a professional football player for the National Football League (NFL). He played for six teams in 78 games over seven seasons as a reserve cornerback. He had been playing the sport since the age of 7 in 1995, and went to Rock Hill High School and South Carolina State University. Joe Montgomery, who coached Adams in high school, said that he was "the role model that all coaches hoped they could coach. He played for South Carolina State from 2005 to 2009. He was a draft pick for the San Francisco 49ers in 2010, and went on to play for the New England Patriots, Seattle Seahawks, Oakland Raiders, New York Jets, and finally the Atlanta Falcons, the team he was on when he retired from football in 2016. 
In 2009, Adams' mother became paralyzed in a car accident, and he worked to support her. Adams also supported a son. Also that year, Adams was arrested for an assault and battery charge in Orangeburg, which he was not convicted of. The same happened when he was arrested for carrying a concealed gun in 2016 in Charlotte. In his rookie season in the NFL, Adams suffered a severe ankle injury that almost derailed his career. Adams' agent said the injury had prevented Adams from "reaching his potential", and that the injury "weighed on him heavily". 
In 2021, Adams was 32 years old, and living in his hometown of Rock Hill in York County, South Carolina. He had moved back into his parents' home on the city's south side. His neighbors had thought of him as a "wounderful young man" and a "quiet, helping presence". Former Cowboys cornerback Kevin Smith claimed that Adams did not use any drugs or drink alcohol. However, after retiring from football, he often isolated himself, even to other players, and fell out of contact with old friends and teammates. His dad said that "he didn't talk much and he didn't bother nobody". 
Adams ran a shop selling smoothies and juice, until the COVID-19 pandemic happened. After the shop failed, he called his agent, who recommended a few jobs in Dallas, as well as to look into the mental health resources the NFL offered. He declined these options, and his agent "suspected Adams' mental health was deteriorating". Adams made numerous notebooks filled with "cryptic" designs and emblems, which made authorities to suspect he became interested in "a new religion or ideology". A neighbor said that Adams would repeatedly pace around his front yard. He owned at least nine guns.
Victims.
There were 6 victims of Adams' shooting in Rock Hill. Four of these victims were of the Lesslie family, who lived on Marshall Road: Dr. Robert Lesslie (age 70), his wife, Barbara Lesslie (69), and their two grandchildren, Adah (9) and Noah (5) Lesslie. Their land was a forested plot with three buildings, one of which was used as their home. Adams lived about a quarter mile away from their house. 
Dr. Robert Lesslie was a prominent local doctor who founded two urgent care centers, wrote medical advice books and a weekly medical column for "The Charlotte Observer", and worked for Camp Joy, a center for children with disabilities. He and Barbara were known for their community service and charity. They were married for 40 years, and had four children and nine grandchildren.
The other two victims were James Lewis (38), and Robert Shook (38), who had been working on the HVAC unit for the Lesslies' house. They were both technicians employed at Gaston Sheet Metal Services (GSM Services) in Gastonia. Both Lewis and Shook had three children.
Shooting.
Adams' shooting took place on Marshall Road at the Lesslies' house on April 7. That day, it had been the birthday of Robert and Barbara's daughter. They were watching their grandchildren while their daughter went out to dinner. That morning, Alonzo Adams had called Phillip's agent. The agent was not available, and Alonzo left a voicemail, calmly saying they needed to talk. A few hours later, Phillip left his house with two guns and his phone, and left on a four-wheeler going west. 
In the evening, Adams shot Lewis and Shook outside the Lesslies' house, and then went inside and shot Robert, Barbara, Adah, and Noah in the back room. Police received two 911 calls around 4:45 p.m. EDT. One was from Shook, who provided details on what happened to him. The other was from a man who was mowing his lawn nearby, who heard about 20 shots fired at the Lesslie house. He went over to the house, and heard gunshots. Once the shots died down, Adams walked out of the house. Both a .45-caliber weapon and a 9mm weapon were used in the shooting. Three dozen casings and more than 20 "projectiles" were found at the crime scene. Police said they did not know where Adams obtained the weapons.
Law enforcement response and Adams' suicide.
The county sent out a phone call to at least one neighbor of the Lesslies, telling her to lock down her house. She also saw Robert and Barbara's daughter, and let the daughter into her (Ferguson's) house. Deputies also visited another neighbor's house, and advised them to stay inside. The York County Sheriff's Office tweeted that detectives were searching for a man wearing a black hoodie and camouflage pants, who was last seen in the area, and may be armed and dangerous. Residents were told to stay inside and lock their doors. 
Alongside police, medical helicopters, an ambulance, and a SWAT team responded to the scene. Police cleared the house, and then found the two repairmen in the yard of the home by their trucks. Lewis was dead, and Shook was still alive then. Authorities then searched the woods with dogs.
Police found evidence that Adams had left at the house that quickly made him out to be the suspect, though they did not state what this evidence was. A manhunt searched for Adams, assisted by a drone and helicopter. It lasted for eight hours, before police found him at his parents' house around 9 p.m. However, a helicopter continued flying through the area until midnight.
The police spent several hours negotiating with Adams using a loudspeaker, trying to get him to surrender. At some point, Adams' parents were evacuated from the house, and police also sent in a robot to scan it. At 1 a.m., the media was briefed that the perpetrator's location had been found. Police found Adams dead inside the house at 2:30 a.m., along with a .45-caliber and a 9mm handgun. The cause of death was listed as a self-inflicted gunshot wound from a .45-caliber handgun. The police said they did not hear the gunshot, although a neighbor heard a shot sound at 12:30 a.m.
Aftermath.
Shook was flown to a Charlotte hospital in critical condition, and was given multiple surgeries. Despite this, he died days later. He was shot at least six times, and the fatal bullet pierced his liver. 
On April 8, the York County Sheriff's Office said in a press conference that the perpetrator was Adams, confirmed by Alonzo. They were also in the process of searching Phillip's home, and said they believed no other perpetrators were involved. All the deaths were investigated as homicides.
The Lesslie family, York City Council, York City Government, President Joe Biden, Governor Henry McMaster, Representative Ralph Norman, GSM Services, and the NFL made statements regarding the shooting. Biden mentioned it in a speech about gun reform on April 8; he said “Gun violence in this country is an epidemic,” using Rock Hill as an example. On April 8, the South Carolina State Senate adjourned in the victims' memory. Ceremonies were held at First ARP Church in Rock Hill and Gaston Steel Mill Services, and a memorial was made at Robert Lesslie's medical office, which continued to operate. A GoFundMe campaign was made for the families of Shook and Lewis, which raised $400,000 that was split between the two of them. The remaining members of the Lesslie family asked that any memorials be made to Camp Joy. They also expressed forgiveness towards Adams.
Rock Hill had been known as "Football City U.S.A.", for the amount of football players that had lived there. The sport had been a "social event, a source of civic pride, [and] a pathway to glory" for the city; after the shooting, this attitude lessened.
In December, Holly Shook, the widow of Robert Shook, filed a wrongful death lawsuit against Adams' estate. The lawsuit claimed that the Shook family suffered extreme emotional distress, as well as damages that exceeded $75,000 "exclusive of interest and costs".
Adams' motive.
The Sheriff's Office said after the shooting that they did not find a motive for the shooting. Adams had had no prior criminal record. The "New York Times" wrote that it was difficult to find a motive in cases where the perpetrator was dead and had not written a suicide note. Ralph Norman said that law enforcement told him that Adams had been seeing Robert Lesslie as a patient: “He was treating him and stopped giving him medicine, and that’s what triggered the killings from what I understand". Alonzo Adams confirmed that he was a patient.
The Adams family suggested that Phillip's football career may have caused brain damage that played a role in the shooting. Alonzo Adams said that he was a "good kid", and that the sport "messed him up". The York County Coroner's Office and researchers at Boston University conducted a study of Adams' brain. In December, an autopsy revealed that Adams suffered from a stage II case of the brain disease chronic traumatic encephalopathy (CTE). "Unusually severe" damage was found in his frontal lobes. CTE is caused by repeated injuries to the head, and can only be diagnosed after death. It causes cognitive decline, and when there is damage on the frontal lobes, it can lead to aggression, impulsive behaviors, a lack of self-control, and a lowering of the threshold it takes for someone to commit a homicidal act. Playing with the Raiders in December 2012, Adams suffered at least two concussions.When Adams received the concussions, it was not clear if they would give him long-lasting injuries. He was not able to get tested for it as a part of the NFL's settlement with players regarding concussions; the settlement was only for players who had retired by 2014. His former agent said he would not consider the agent's health tips regarding disability. Adams' sister said his personality changed a few years prior to 2021, when "he became argumentative". By 2021, Adams had been suffering decreased mental health, intense pain, memory issues, and difficulty sleeping. He had tried to get help via a disability claim with the NFL multiple times; his family says his request was denied due to his inability to remember certain things and perform simple tasks, yet those effects were likely the result of his disease. Adams' sister said that he had been expressed resentment towards the NFL two weeks prior to the shooting, and that his inability to the collect a claim from them made him feel like the "world was against him".
Dr. Ann McKee of the Boston University CTE Center said that Adams' case of CTE was