SAN JOSE (CBS SF) – Valley Transportation Authority officials on Thursday released documents about the gunman who killed nine of his colleagues at the light rail yard in San Jose last month, including an account from a colleague who feared him.

The agency released details Thursday from an initial review of the personnel file of Samuel Cassidy, more than two weeks after the shooting. Cassidy, a 20-year employee of VTA, killed co-workers at the facility on May 26, before taking his own life.

According to the documents, the agency found four separate incidents within the past two years that were elevated to management.

VTA said in early 2020, a verbal altercation between Cassidy and an unnamed coworker was reported to the agency’s Employee Relations department and Office of Civil Rights. During questioning by a supervisor, an employee reported that another colleague said about Cassidy, “He scares me. If someone was to go postal, it’d be him.”

Officials said the worker refused to name the colleague who made the statement.

Despite that incident, the VTA did not feel there was anything in Cassidy’s file that had raised red flags.

“Upon further investigation, there was nothing in Cassidy’s disciplinary history, or additional information to explain or support that concern,” the agency said Thursday. VTA is continuing to search for any additional documents from the incident.

Back in July of 2019, the agency said Cassidy was sent home without pay for two days for insubordination after he refused to follow company policy in signing out a two-way radio needed for his job.

The other incidents where Cassidy was reported to management include when he refused to attend a mandatory CPR class citing COVID-19 concerns back in October and unexcused leave and inappropriate use of a VTA radio the following month.

VTA officials said they have not found any documents or history of complaints of Cassidy making racist or threatening remarks. The agency also said they did not receive information from the Department of Homeland Security or any other federal agency about Cassidy.

The Wall Street Journal reported that Cassidy was detained by U.S. Customs and Border Protection following a 2016 trip to the Philippines. According to a Homeland Security memo obtained by the Journal, Cassidy had “books about terrorism and fear and manifestos … as well as a black memo book filled with lots of notes about how he hates the VTA.”

Cassidy reportedly told agents he had no problems with people at work.

VTA officials said there are “thousands of pages” of documents related to the case still needing review.