David Leach, publisher of Prayer & Action News, a magazine that opines that the killing of abortion providers would be justifiable homicide, told reporters that he and Roeder had met once in the late 1990s and that Roeder at that time had authored contributions to Leach's publication.
 Leach published the Army of God manual, which advocates the killing of the providers of abortion and contains bomb-making instructions, in the January 1996 issue of his magazine. A Kansas acquaintance of Roeder's, Regina Dinwiddie, told a reporter after Tiller's murder (speaking of Roeder), "I know that he believed in justifiable homicide." Dinwiddie, an anti-abortion militant featured in the 2000 HBO documentary Soldiers in the Army of God, added that she had observed Roeder in 1996 enter Kansas City Planned Parenthood's abortion clinic and ask to talk to the physician there; after staring at him for nearly a minute, Roeder said, "I’ve seen you now," before turning and walking away.
Roeder's former roommate of two years, Eddie Ebecher, who had met Roeder through the Freemen movement in the 1990s, told a reporter after Tiller's murder that he and Roeder had considered themselves members of the Army of God.
Ebecher said Roeder was obsessed with Tiller and discussed killing him, but that Ebecher warned him not to do so. Ebecher, who went by the nom de guerre "Wolfgang Anacon," added that he believed Roeder held "high moral convictions in order to carry out this act. I feel that Scott had a burden for all the children being murdered."
In 2007, someone who identified himself as Scott Roeder posted on the website of the anti-abortion group Operation Rescue that, "Tiller is the concentration camp 'Mengele' of our day and needs to be stopped before he and those who protect him bring judgment upon our nation."
This was reported by the ADL's Center on Extremism, noting that Roeder called for "the closing of his death camp."  After Tiller's murder, officials from Operation Rescue, which had long opposed Tiller's abortion practices but denounced his shooting, said Roeder was not a contributor or member of the group. The phone number for Operation Rescue's senior policy advisor, Cheryl Sullenger, was found on the dashboard of Scott Roeder's car. At first, Operation Rescue's senior policy advisor Cheryl Sullenger denied any contact with Roeder, saying that her phone number is freely available online. Then, she revised her statements, indicating that Roeder’s interest was in court hearings involving Tiller.