• Check the character set/collation a given table uses:

SELECT CCSA.* FROM information_schema.`TABLES` T,
       information_schema.`COLLATION_CHARACTER_SET_APPLICABILITY` CCSA
WHERE CCSA.collation_name = T.table_collation
  AND T.table_schema = "db_webqtl"
  AND T.table_name = "Investigators";

• Fixing broken character-sets:

ALTER TABLE Investigators CONVERT TO CHARACTER SET BINARY;
ALTER TABLE Investigators CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

Read the following for more details:

• Debugging character-set issues by example