can someone name this anime film?

can someone name this anime film? I am trying to rediscover an anime movie that i saw on american television somewhere in late 90's or early 2000's. here is what i remember: the movie takes place in a somewhat futuristic Tokyo/urban metropolis. there is a giant monster that hides in the tokyo bay or something. throughout the movie, there are police investigators trying to find out what is killing random people (it is the giant monster), while (if i remember correctly) if i remember correctly, investigating the case of a missing woman. there is a scene where the police squad goes into a big warehouse and its pitch black and the giant monster (if i remember, it had red coloring, has tentacles on body, large mouth full of sharp teath) kills almost every squad member. near the end of the movie, a woman in a white dress, who is seen periodically throughout the film and who (if my memory is correct) is who the police are trying to find, dies by falling into a sports stadium, i think it is a baseball park or something, where the final battle with the monster vs a robotech suit protagonist takes place (at night, and in the rain i think). i think she killed herself by falling because she was sad that the monster died because it was her "child". before that battle, there is a scene where the monster is heading towards the stadium through the cities waterways, fighting through amphibious robotech vehicles. I think that the stadium was a trap that the investigators set up. it turns out, somwhere in the plot, that the mysterious woman is the monster's MOTHER, and that the monster (if my memory is right) was a mutation of her DNA, and the monster was trying to be ruinited with the mother.