A 20-year-old Naval Academy midshipman who died in October took his own life, the medical examiner’s office has determined.

Kyle Philbert James of Whippany, New Jersey, died of hydrogen sulfide intoxication, according to Stephanie Moore, a spokesperson for the Office of the Chief Medical Examiner in Baltimore.

A flammable, colorless gas that smells like eggs, hydrogen sulfide affects the respiratory, cardiovascular and nervous systems if inhaled quickly, according to the Agency for Toxic Substances and Disease Registry.

It’s unclear when the office made the determination, which seems to resolve some mystery around James’ disappearance.

His mother, Dyane, told a Connecticut television station that a battalion officer at the Naval Academy informed her on the afternoon of Oct. 9 that her son hadn’t shown up for any of his classes.

She showed WFSB Eyewitness News 3 a text message that she sent her son Thursday morning, to which he replied, “I love you more.”

A spokesperson for the Annapolis service academy did not immediately respond to a request for comment Thursday.

An obituary published by Carmon Community Funeral Homes described James as an intelligent, high-achieving student. It said his family “loved him boundlessly.”

“His success in life brought them such light and joy,” the obituary said. “As he became an adult, his heart, his ethics, and his strength made them proud beyond measure. When he was home or with his family, he enjoyed shopping, going out to eat, watching movies, and traveling both domestically and abroad.”

“His passion for learning and people made him a pleasure to talk to, be with, and experience life with.”

If you or someone you know needs help, the national suicide and crisis lifeline in the U.S. is available by calling or texting 988. There is also an online chat at 988lifeline.org

This article may be updated.