An American chemistry teacher shot to death while jogging in Benghazi was looking forward to his first Christmas in the United States with his wife and son.

Ronald Thomas Smith II shared his excitement with his students, and sent his wife and child home while he stayed in Libya a few more weeks to help the young people in his class complete their end-of-semester exams.

His death on Thursday shattered those dreams and highlighted the tenuous security in the eastern Libyan city where a U.S. ambassador and three other Americans were killed last year.

But to Smith’s students, this was more personal. He was a teacher who offered free private tutoring when others had given up, they said. Smith pushed them, demanding hard work and success.

More than anything, he talked and laughed with them, and loved their country.

“He wasn’t just a teacher to all the students, though — he was a brother,” said Abdulrahman Bader, a 16-year-old student. “He was the heart of the school.”

Smith graduated in 2006 from the University of Texas in Austin with a master’s degree in chemistry. During his years in Texas, he was active in the Austin Stone Community Church, fulfilling what friends described as Smith’s strong Christian beliefs. About 18 months ago, Smith began teaching at Benghazi’s International School, a Libyan-owned facility that follows a British curriculum.

“Ronnie’s greatest desire was for peace and prosperity in Libya and for the people of Libya to have the joy of knowing God through Christ,” Dave Barrett, executive pastor of the Austin church, said in an emailed statement.

Smith’s wife, Anita, and their son were already in the United States and “safe with family” when he was killed, Barrett said.

Smith was an integral part of the school just outside Benghazi, taking trips to the beach with his students and visiting their homes to tutor them while snacking on sandwiches and watermelon. He also became active in their online chatter on Twitter — where many of them went to confirm rumors of his death and to share their anguish and memories.

Under #MrSmithMemories and #ThankYouSmith they wrote about how he baked them cookies and sang “Happy Birthday” to them in Arabic, taught them “to think like the electron and be the electron” and shared the story of how he met his wife.

“He was a much loved teacher who supported students in their learning and always had time to help when asked,” the school posted on its Facebook page. “Ronnie was a professional who gave his time freely and without question. We do not understand why this has happened and it is extremely difficult for his students and his colleagues to accept.”

Omaima El-Faitori, 15, was in her second year of learning chemistry with Smith. He was “not only a teacher, he was like a best friend to me,” she said.

On his Twitter handle, @ISBchem, Smith described himself as a best friend of Libya. El-Faitori said that was most certainly true. Smith loved Libyan food, most of all masareen, a dish of stuffed sheep intestines.

Smith also used his Twitter account to comment on the security situation and he didn’t shy from black humor about the rampant militias that roam the city.

“I understand I teach at a school of rich kids, so if (and when) I’m kidnapped by Ansar Al-Sharia, who’s gonna pay the ransom?” he tweeted, naming one of the most well-known militias. And on Nov. 25, he tweeted: “I’m going out. If I don’t come back alive know that all your grades have been securely recorded.”

Smith went to Libya after scrapping plans to get a doctorate in chemistry or go to the seminary.

“He had a heart for Libya” and “saw it as a great opportunity to help people,” said Nathan Hlavin, Smith’s friend of 20 years.