dr. davidson: business as usual is not really an option. our economy is based upon having tourists wanting to come here and spend time here. they're not gonna come here if the estuaries are full of algae that smell rotten. so it's extremely important, and we're getting to a tipping point where we have to do something. and i think the same is true across the globe. dudley: we know that people are still gonna want to come to the cape and that growth is gonna continue, so what we're really interested in trying to do is appropriately manage that growth. we believe that we can still save the habitat and that it isn't beyond a point of no return, and that's what we're actively trying to do. narrator: by combining census data with physical data collected in field studies, scientists can increase the accuracy of their models and help planners and policy makers prepare for future growth. dr. riche: what i do, essentially, is give people the base to look into the future, because we make connections between people and all these things that have costs.

dr. fong lee is the medical examiner for davidson county. >> when you get on the scene, this looks like it could be a double homicide. you later concluded what? >> that mr. mcnair was a victim of a homicide. the female victim was a victim of suicide. >> chris: for police, it was a simple crime of passion. >> reporter: when you heard that police said this is a murder suicide... >> yeah, right. yeah, right. >> chris: those closest to jenni and mcnair say nashville pd dropped the ball. >> reporter: do you think there was a gun sale? do you think he sold a gun for jenni to kill steve and herself? >> absolutely not. >> reporter: why not? >> that's a bogus story if i've ever heard one before. >> chris: so, friends and family don't think jenni pulled ?and why? >> i can tell you who didn't kill steve. that 5-foot to jenni kazemi. >> chris: next, we go looking for answers. >> my name is andrea isom, i am with a show called "crime watch daily." ? ? what? finally, i thought he'd never leave... tv character: why are you texting my man at 2 a.m.? no... if you want someone to leave you alone, you preten