Kim was tortured and sentenced to death.
According to 'Baekbeom Ilji', however, many Korean people were sympathetic and admired him for his patriotism and bravery, as shown by the facts that his execution was suspended by order of Emperor Gwangmu, that Korean judicial officials behaved politely to him despite Japanese pressure to execute him promptly, and that influential Koreans at the time (including major merchants of Incheon) made efforts to rescue him by repeated petitions to Korean Justice Department Officials and by collecting money for his ransom before his scheduled execution date.

In prison, Kim had a chance to read newly published textbooks about Western culture and science such as Taeseo Shinsa (태서신사; 泰西新史) and Saegye Jiji (세계지지; 世界地誌).
He was deeply impressed by the strengths of the new Western science and recognized the importance of education for the Korean people.
He started to teach about 100 illiterate fellow prisoners.
The Korean newspaper Hwhangsung Shinbo (황성신보; 皇城新報) reported at the time that by his teaching of prisoners Kim Chang Soo changed the Incheon Prison into a school.

In 1898 he broke out of prison and escaped into Magoksa, a Buddhist temple in Gongju, Chungcheong province, and entered the Buddhist priesthood.
A year later Kim left the priesthood and returned to Hwanghae, where he devoted himself to the enlightenment and education of the Korean people, founding Jangyeon School (장연학교; 長淵學校) and the Yangsan School (양산학교; 楊山學校) in 1907, becoming the principal of the Yangsan School.
In 1904, he married Choi Jun-rye (최준례; 崔遵禮) from Sinchon, Hwanghae Province.
Kim was tortured and sentenced to death. According to 'Baekbeom Ilji', however, many Korean people were sympathetic and admired him for his patriotism and bravery, as shown by the facts that his execution was suspended by order of Emperor Gwangmu, that Korean judicial officials behaved politely to him despite Japanese pressure to execute him promptly, and that influential Koreans at the time (including major merchants of Incheon) made efforts to rescue him by repeated petitions to Korean Justice Department Officials and by collecting money for his ransom before his scheduled execution date.
In prison, Kim had a chance to read newly published textbooks about Western culture and science such as Taeseo Shinsa (태서신사; 泰西新史) and Saegye Jiji (세계지지; 世界地誌). He was deeply impressed by the strengths of the new Western science and recognized the importance of education for the Korean people. He started to teach about 100 illiterate fellow prisoners. The Korean newspaper Hwhangsung Shinbo (황성신보; 皇城新報) reported at the time that by his teaching of prisoners Kim Chang Soo changed the Incheon Prison into a school.
In 1898 he broke out of prison and escaped into Magoksa, a Buddhist temple in Gongju, Chungcheong province, and entered the Buddhist priesthood. A year later Kim left the priesthood and returned to Hwanghae, where he devoted himself to the enlightenment and education of the Korean people, founding Jangyeon School (장연학교; 長淵學校) and the Yangsan School (양산학교; 楊山學校) in 1907, becoming the principal of the Yangsan School. In 1904, he married Choi Jun-rye (최준례; 崔遵禮) from Sinchon, Hwanghae Province.
Kim Gu