public string URI {get;}

// get the active investigation view 
var iv = KnowledgeGraphInvestigationView.Active;
var serviceUri = iv.Investigation.ServiceUri;

// build a dictionary of records
var dict = new Dictionary<string, List<long>>();
//Each entry consists of the type name and corresponding lists of ids
dict.Add(first_entity, new List<long>() { 1, 5, 18, 36, 78 });

//Create the id set...
var idSet = KnowledgeGraphLayerIDSet.FromDictionary(new Uri(serviceUri), dict);

// select the records on the investigation view
iv.SetSelectedRecords(idSet, SelectionCombinationMethod.New);