Or, entries in Max's medical records by RNs or other staff that document exactly what time she was seen at the bedside. It is commonplace for staff to document visitors present, or "mother ABS" something similar. Most charting software (or old fashioned paper ICU flowsheets) has a specific area in which to document psycho/ social information, such as the presence of parents/ guardians in pediatric patients. In an ICU, RNs would be documenting in the record many times per hour. Some of that documentation would include comments about who was at the bedside.
At this long duration (2+) years, I think the memories of staff members of who was at the bedside exactly when would become more than a little a bit foggy, and unreliable. (Dina wasn't there that much at the beginning of Max's admission by her own report.) At that point (before Rebecca's death), why would staff be noticing more than they usually do who was at the bedside?? I couldn't probably tell you which relatives of my patients were in the pre-op holding room from a week ago, using my memory alone. I'd rely on documentation in the notes as the most reliable. And since police were unable to establish where Dina was from security cameras (many of them in a hospital!), or any other eye witness, they had to resort to triangulating her phone. The cell phone triangulation is pretty far down on the decision making tree when establishing where someone was who CLAIMS to have been at the bedside in a busy pediatric ICU.
Dina certainly has access to her son's medical records. If there were any documentation that directly placed her at the bedside during the time in question, certainly Dina would have shared that by now. She was very willing to post Max's EMS record on one of her websites, so why wouldn't she post relevant snippets to verify her presence in the ICU?
My strong opinion is that there is nothing in the record that places her at the bedside during the time in question, or we would have seen it by now. I do think it's a strong possibility that Max's records will be subpoenaed in the civil suit discovery to document whether there is anything about her presence documented. JMO, IMO, Moo, etc.