Bartkus’ writings indicate that he opposed people being born against their choice and called for the abolition of childbirth and the eventual extinction of mankind.
The FBI has labeled the explosion a “intentional act of terrorism” and stated that the fertility clinic was specifically targeted.
Bartkus lived in Twentynine Palms, a tiny city located about 150 miles (240 kilometers) east of Los Angeles.
Authorities said Bartkus placed explosives into his 2010 silver Ford Fusion automobile and drove an hour from Twentynine Palms to Palm Springs.
The explosion was felt almost a mile away.
At a news conference on Wednesday, US Attorney Bill Essayli stated that Mr Park and Bartkus spent time together doing experiments in Bartkus’ garage.
Several days after the explosion, Mr Park traveled to Denmark and then Poland, but was detained by Polish officials and returned to the United States, where he was imprisoned.
He appeared in federal court in New York for a brief hearing on Wednesday, sporting a T-shirt with the words “Fight Like Ukrainians” printed on it and a large white bandage on his right hand, according to CBS News, the BBC’s American partner.
He waived his right to a detention hearing, admitted to knowing the charges against him, and was transferred to the Metropolitan Detention Center in Brooklyn.
According to Akil Davis, assistant director in charge of the FBI’s Los Angeles field office, Mr Park “was in possession of an explosive recipe that was similar to the Oklahoma City bombing.”
According to investigators, the duo discussed their plans online and were members of an anti-natalism movement, sometimes known as pro-mortalism or efilism.
The movement has various branches and offshoots, but it generally believes that because there is so much suffering, it would be preferable if humans and other living forms become extinct.
Mr Davis described the fertility clinic as “the largest bombing scene” the FBI had seen in southern California in recent years.
The bomb caused damage to several buildings, including the fertility clinic, which had a part of its wall shattered, according to pictures.
According to its website, the ARC Clinic is the Coachella Valley’s first full-service reproductive center and IVF facility.
It provides fertility examinations, IVF, egg donation and freezing, reproductive support for same-sex couples, and surrogacy.
