public sealed class KnowledgeGraphInvestigationProjectItem : KnowledgeGraphBaseProjectItem, ArcGIS.Desktop.Core.IMetadata, ArcGIS.Desktop.Core.IProjectItem, ArcGIS.Desktop.Mapping.IMappableItem, System.ComponentModel.INotifyPropertyChanged  

// open an existing investigation
var investigationProjectItems = Project.Current.GetItems<KnowledgeGraphInvestigationProjectItem>();
var investigationProjectItem = investigationProjectItems.FirstOrDefault(ipi => ipi.Name.Equals("myInvestigation")); 
await QueuedTask.Run(async () =>
{
  KnowledgeGraphInvestigation investigation = investigationProjectItem.GetInvestigation();
  await ProApp.Panes.CreateInvestigationPaneAsync(investigation);
});

//Confirm if investigation exists as a project item
KnowledgeGraphInvestigationProjectItem investigationItem = Project.Current.GetItems<KnowledgeGraphInvestigationProjectItem>().FirstOrDefault(
                                                      item => item.Name.Equals("myInvestigation"));
if (investigationItem != null)
{
  KnowledgeGraphInvestigation investigation = await QueuedTask.Run(() => investigationItem.GetInvestigation());

  // see if a view is already open that references the same investigation
  foreach (var investigationPane in ProApp.Panes.OfType<IKnowledgeGraphInvestigationPane>())
  {
    //if there is a match, activate the view
    if (investigationPane.InvestigationView.Investigation == investigation)
    {
      (investigationPane as Pane).Activate();
      return;
    }
  }
}