On May 15, 2022, a mass shooting occurred at the Geneva Presbyterian Church in Laguna Woods, California, United States.

[9] After the service, the church goers gathered in a separate hall for a luncheon in Chang's honor, and some guests who left early saw the shooter attempting to lock the doors with chains.

[39][40] In 2019, Chou attended the founding ceremony of Las Vegas Chinese for Peaceful Unification and displayed a banner calling for the "eradication of pro independence demons".

Chou's mental stability appeared to diminish, telling his former neighbor "I just don’t care about my life anymore.”[28] He once fired a gun without injuring anyone.

[44] Other tenants have found photographs of Chou posing with a gun and laughing hysterically at a memorial for the 2017 Las Vegas shooting.

[28] Two weeks before driving to Laguna Woods, Chou told his roommate that he felt the Taiwanese government was corrupt and disliked those who were sympathetic to its leaders.

[45] He had allegedly written a manifesto entitled Diary of the Independence-Slaying Angel (滅獨天使日記) and mailed it to the pan-blue World Journal.

[4][5] Sheriff Don Barnes said that handwritten notes recovered from a vehicle expressed Chou's "hatred for the Taiwanese people" and belief that Taiwan should not be independent from China.

[5] U.S. Representative Katie Porter, whose district includes Laguna Woods, also referred to an earlier shooting in Buffalo, New York and said, "This should not be our new normal.

Hsiao Bi-khim, Taiwan's de facto ambassador, posted on Twitter that she was "shocked and saddened by the fatal shooting" and would mourn with the Taiwanese-American community and victims' families.

[25][53] In Taiwan, DPP legislator Lin Ching-yi attributed the shooting to “genocidal ideology”, and 60 civic groups called for the designation of Chinese for Peaceful Unification as a terrorist organization.

[54] Although not necessarily the same group, the National Association for China's Peaceful Unification has been accused of at times extremist messaging by Michael Cole, a fellow at the Macdonald–Laurier Institute.

[43] Wang Wenbin, a spokesperson for China's ministry of foreign affairs, said, "[W]e hope the US government can take action against its increasingly severe gun violence problem".

[25] Liu Pengyu, spokesperson for the Chinese Embassy in Washington, said, "We express our condolences to the victims and sincere sympathy to the bereaved families and the injured.

[55] In June 2022, Representatives Katie Porter and Michelle Steel proposed a bill to posthumously award the Congressional Gold Medal to Cheng.