I couldn’t find any details about the life of actress, Jennie Costello. I was able to locate another cabinet card image of Miss Costello but nothing else. I guess she was in the witness protection program and all information pertaining to her life has been erased. The actual explanation is probably that she was not a major stage star and my search for information lacked enough depth to shed light on her career. This portrait was produced by the Hartley studio in Chicago, Illinois. Edward Hartley printed a drawing of his studio’s storefront on the reverse of this cabinet card (see the image below). He was a rabid self promoter which will be evident after you examine more of his photographs and read their descriptions. You can accomplish this feat by clicking the category “Photographer: Hartley”.
THE CABINET CARD GALLERY 
Nice backstamp!
was she actually in the WPP or are you kidding ?
I was kidding. I was trying to explain how much difficulty I had finding information about this actress. It was “as if” she was in the federal witness protection program. The actual witness protection program was established by the federal government in 1970. However, it would not surprise me if the government had been relocating witnesses on a more informal basis for years prior to the official program.