A man accused of fatally stabbing a woman aboard a MARTA train is now in custody, as the violent attack raises new concerns about safety across Atlanta’s transit system.

According to police, 52-year-old Margaret Swan was riding a MARTA train near the Oakland City Station on May 30 when she was stabbed to death.

Investigators say officers quickly arrested the suspect, identified as John Elijah Matthews, at the station shortly after the attack.

Swan’s ex-husband, Jerry Swan, said he was devastated when his daughter called to tell him what happened.

“I was happy they caught him, but in my mind the thought was why did he do that to such a nice person,” he said.

Jerry Swan described Margaret as a devoted grandmother who loved spending time with her family.

“She was on her way to keep one of her grandbabies when it happened,” he said.

The deadly stabbing has also left some MARTA riders uneasy about safety on the transit system.

Nahsar Alexander, who says he rides MARTA every day, told CBS News Atlanta the attack is alarming.

“That was an innocent lady,” Alexander said. “If she didn’t do anything, what’s stopping someone from hurting me?”

MARTA officials say nearly 300 officers are assigned throughout the transit system to help keep riders safe. Additional officers were visible Monday at stations, including patrols on motorcycles.

The agency says security measures are also expected to increase ahead of the FIFA World Cup, when Atlanta is expected to see a major influx of visitors.

MARTA says its current security resources include more than 12,000 cameras across rail stations, buses and railcars, along with a Real Time Crime Center monitored during operating hours. Officials also say undercover officers regularly patrol stations, buses and trains.

Ahead of the World Cup, MARTA plans to activate its Emergency Operations Center during matches and fan events, deploy its Mobile Command Vehicle at key locations and partner with outsidxe law enforcement agencies for additional support.

Officials say additional train patrols and crowd control teams will also be used throughout the system.

Some riders say the increased police presence is reassuring, but concerns remain.

“Yes, but even with more police officers crime is still going to happen,” Alexander said.

Matthews is facing a murder charge.

MARTA says all staff not directly involved in operations or policing will also serve as Transit Ambassadors during the World Cup to assist riders and monitor activity across the system.