Robert Dear, Jr., reportedly screamed I’m guilty in a preliminary hearing, and shouting out in court on several occasions.
Briefly quoting the FOX news report linked above:
Later, while Judge Gilbert Martinez was discussing the possibility of a gag order, Dear yelled “Seal the truth, huh? Kill the babies, that’s what Planned Parenthood does.”
“You’ll never know what I saw in that clinic,” Dear said, “the atrocities—the babies.”
Evidently Dear was indeed an anti-abortion activist, as early speculation had it.
With the fact of his guilt and motive self admitted, the major mystery is what gun Dear used. While it is a minor mystery, it is a loose end.