definitively serrano s, but very much like one he once owned and experts examined. the wear pattern is consistent with the shoe that stepped on that vinyl chair in december of 1997? absolutely. reporter: prosecutors knew they would have to shred serrano s alibi that he was in atlanta for a business trip and not in florida for the lethal business of murder. people would go to atlanta, they would find him on the videotape, he would be alibied and nobody would ever look any further. and that would be the end of it. in terms of being diabolical, that s a pretty good alibi. reporter: they laid out their evidence for serrano being in florida that day. they called the nephew who rented a car for his uncle and he told a damaging story. the day after the murders, he said his uncle ordered him to retrieve that same car in the tampa airport parking garage and drop it off at the rental company.
there were allegations that nelson serrano had stolen a quarter of a million dollars. after threatening lawsuits and one shouting match too many, the founding partners, dosso and gonsalves, fired serrano and his son and then they changed the locks to the office. but serrano didn t leave quietly. within weeks of being ousted, he tried to force his way back into the building. partner george gonsalves called the cops. 911 emergency. do you need police, fire or ambulance? someone s breaking a door down. is it someone you know or a former employee or what? yes, former employee. okay, what is his name? nelson serrano. reporter: then six months later, december 3, 1997, came another 911 call from erie manufacturing. four dead, shot execution style. given serrano s stormy relationship with his partners, homicide detectives asked him to give a taped statement the day
after the killings. i have no idea what even happened, where it happened, when it happened, how it happened. reporter: serrano talked to police willingly, sharing details of a business partnership gone awry. we never had any problems until we started making serious money. reporter: even speculating on how the murders went down. there were many people involved. i mean there are four people in there. one guy is going to go over there and kill four people? reporter: serrano told police he was in atlanta, 500 miles away from erie manufacturing, on the day of the murders, holed up in his motel room, door locked, drapes pulled suffering from a migraine. and an airport hotel security camera seemed to bear his story out. here he is on tape at an atlanta la quinta inn, in the lobby, around noon on the day of the massacre. he walks into frame again about 10:00 that night. agent tommy ray s team, of course, had his alibi checked out. we got a phone call from the
reporter: defense team bob norgard and cheney mason were relentless in their cross-examinations of witnesses, starting with the investigators who gathered evidence. 12 bullet casings, for instance, told them nothing about who loaded the guns. with respect to the casings, no fingerprint evidence linking those casings to mr. serrano? that s right. reporter: no serrano fingerprints found anywhere around the crime scene. not a single fingerprint was linked to mr. serrano in that building, isn t that true? none of the fingerprints were linked to him. reporter: the dusty shoeprint seemed to be serrano s shoe size. can you tell me how many shoes there are that match no, i cannot. 2 million, 10 million, 100 million? do you know? i really don t know. this is all part of a circumstantial case. you have to believe each link in the chain to get him to make that footprint in the chair. what is the theory here? there are three men in there, 200-plus pounds each. excuse me
reporter: the prosecutor introduced the gruesome crime scene photos, bullet casings and bodies that accompanied the story that he told the jury about a one-time business partner s homicidal revenge, the bitter loser in a fight for control of the company. and when jurors went to tour the murder scene itself, the prosecution explained its theory of why that ceiling tile had been moved and why there was a dusty footprint on the chair beneath. employees testified that serrano, a gun enthusiast, kept handguns in his office and may have stashed at least one away in the dropped ceiling. same day you see him getting something out of the ceiling is the day you see the gun? yes. reporter: behind the tile, likely prosecutors say where he kept the .32, one of the two guns used that night. there was only one person that we heard about that would have an interest in that ceiling tile and that s the guy that maybe left a gun up there that he don t want the cops to find. reporter: and as f