The official pronouncement of everyone associated with "Columbo" is thatthe character played by Kate Mulgrew, in the series initially called "Mrs Columbo," was married to some other cop who happened to also be named Columbo.

"Mrs Columbo" was the brainchild of NBC entertainment president Fred Silverman, who hoped to carry on a little of the "Columbo" mystique without Columbo, soon after "Columbo" ended its NBC run. Richard Levinson and William Link regarded the idea as heresy, but Silverman said he'd do it without them. "The magic of Columbo's wife is that you never see her," Levinson protested.

Mulgrew's Kate Columbo was a part-time reporter for a pennysaver newspaper, who often found herself engaged in crime-solving.

Apart from the off-camera statements by the "Columbo" creators, the shows themselves provide evidence that the Kate Mulgrew character was not the wife of the famous Lieutenant.  In one of several major changes over the series, Kate Mulgrew's character was DIVORCED and took on the name Kate Callahan.

But it is clearly known in "Columbo" that the Lieutenant has never been divorced.