LOS ANGELES, California (CNN) -- Relatives of one of the 25 people killed in a train collision last week said Tuesday they intend to sue the Metrolink commuter rail system.
"I'm here to fight for my sister," said Juan Magdeleno, brother of 19-year-old Aida Magdeleno, who died in the crash. "I know that's what she wants. She was an activist at heart."
He broke into tears as he said: "Metrolink needs to make changes now ... I'm holding them accountable."
Twenty-four bodies were found at the scene after a Metrolink train slammed head-on into a freight train in suburban Los Angeles at about 4:30 p.m. PT Friday. A 25th person, a man in his 50s, died later at a hospital.
More than 130 people were injured. The commuter train was carrying 220 people.
Metrolink said a day after the crash that it appeared its engineer -- identified as Robert Martin Sanchez, 46 -- had failed to heed a stop signal.
The National Transportation Safety Board, which is investigating the cause of the crash, said it is looking into reports the engineer -- who was killed in the wreck -- sent text messages on his cell phone moments before the crash happened.
The NTSB has subpoenaed records from Verizon Wireless, NTSB spokeswoman Kitty Higgins said Monday. The agency said it communicated with two teenagers who told a local television station they were exchanging text messages with the engineer just before the crash occurred.
"The time has come to use this tragedy as a way to bring change that will prevent other families from having to sit in an office like this and make a statement, as this family is making today," said Paul Kiesel, an attorney representing the Magdelenos.
Metrolink forbids train operators from using cell phones or other electronic devices while on duty.
On Monday, Michael R. Peevey, president of the California Public Utilities Commission, said he was proposing an emergency order banning use of cellular devices while operating a train. He said he would call on the Federal Railroad Administration to institute additional train control safety measures.
Among those killed in the crash was Spree Desha, a Los Angeles police officer on her way home from work. California Gov. Arnold Schwarzenegger said in a statement Tuesday that capitol flags will be flown at half-staff in honor of Desha, a seven-year veteran of the LAPD.
"She selflessly dedicated her life to protecting the city of Los Angeles and her commitment to public safety will never be forgotten," Schwarzenegger said.
Funeral services for Desha are scheduled for Thursday.
CNN's Irving Last contributed to this report.