With all due respect to other posters, KCPD *did* inform the public the last time that Lisa was seen. The Amber Alert included that information. They quoted the mom as saying she was last seen about 10:30, 10:40 p.m. Steve Young repeatedly said that in his initial news conferences.
And then Mom began to publicly change her story and the timing. That obviously cast even more suspicions on her actions.
A neighbor has recently come forward and said he hung out with SB and DB for roughly 90 minutes and didn't see any sound or anything related to Lisa including hearing her via a baby monitor (meaning DB didn't have one on her).
Based on this changing timeline and that KCPD no longer considers this a missing persons case, why would they make something public (last time that she was seen) that could hinder their investigation? Other than satisfying armchair sleuths, what does KCPD or FBI gain by releasing that information? And if this is ever brought to trial, ensuring the defendant gets a fair trial is also important. Would I love to know? Sure. But I don't expect KCPD to tell us. And we know that DB's attorneys and herself are now saying the last time she saw Lisa was 6:40 p.m. or so.
Other than SB and her daughter, I don't know what witnesses are being quiet at this point.