Dateline | April 10, 2013
>>> joe morrissey had been savagely stabbed to death in a home invasion that ended with his family's house set ablaze. now, police were trying to figure out who could have committed such a brutal crime. kay 's daughter from her first marriage, christina, first thought it might have something to do with the renovations her mom and joe were having done at the home.
>> i honestly thought maybe it was the contractors because they had had a lot of people coming in and out of their house doing work. i never thought that it was somebody who they knew.
>> like some random thing in which people came in to rob the house.
>> yeah. that was my first --
>> and everything went wrong.
>> yeah. that was my first guess.
>> who didn't like joe ?
>> the only person that i knew of that didn't like him was his ex-wife and her family. it was a nasty divorce. there were just bitter feelings there.
>> reporter: police looked into joe 's previous marriage but determined it had nothing to do with the crime. investigators did have one narrow thread to pull on. something kay had mentioned to them.
>> the only thing she was able to tell me was a brief description of what the suspect who first entered the house looked like.
>> reporter: kay had not recognized that man at the time. only later did she realize she might have seen him once, several months earlier. joe had been a scientist, a husband, and a father. but he was also a landlord, and kay thought the man might be related to the tenants at a townhouse they owned.
>> i found a family member who could match the description of what kay gave me in her initial statement. checking more into this person, i found he had a warrant for his arrest.
>> what was his name?
>> randy tundidor jr .
>> reporter: and with that name the investigation was now heading from the loving morrissey family to the other family in this story. randy tundidor jr . was 21 and into drugs, with an arrest warrant for violating his probation on a burglary rap.
>> did you go talk to him?
>> we couldn't find him.
>> reporter: but detectives could find his father, randy sr ., at the townhouse. randy sr . said he hadn't talked to his son in a while. and when police went looking for randy jr . at the family window-tinting business, called gator tint, an alert officer noticed something suspicious.
>> a k-9 sergeant sees stuck between the lid of the dumpster and the dumpster itself a zip tie . i drive down there. i immediately identify it as the same make, size of the ones used in the murder. that's a solid piece of evidence.
>> that's your first break.
>> reporter: randy sr . allowed police to search the business without a warrant.
>> immediately we see there's a bag of the same type of wire ties that were used to tie up joseph morrissey . they also sell knives at the business. there's a empty box that holds a 15-inch bowie knife . when he's asked, where's the knife that belongs to this box, he tells us it should be there. he doesn't know where it is.
>> do you think at this point he's covering up for his son?
>> i think that he's aware that things are not going good for his son. but it doesn't seem like he wants to cover for his son.
>> so this is a good citizen letting the police do their investigation.
>> and if the chips fall on his son, then they do?
>> okay, randy .
>> reporter: investigators eventually located randy jr . and brought him in for questioning.
>> randy jr . seemed composed, very interested to know what information i had about the case. very willing to talk to me.
>> if i didn't have a warrant, i would have freely talked to you guys.
>> no problem.
>> i don't have no connection with this murder. i don't know who did it. i want to clear my name because i did not commit this murder.
>> reporter: and as for that knife that was missing from his dad's shop, randy jr . had an explanation for that.
>> he had stolen that knife weeks earlier and had sold it to a friend of his that he knows on the street.
>> i used to buy dope off of him. so i'm positive he still has it.
>> i ask him to further describe the knife, and he draws a picture, and it's an exact replica of the knife that we believe to be used in the murder.
>> reporter: over the course of two days of interrogation randy jr . denied any involvement in the murder.
>> it could have been a random hit. you never know what it is.
>> it's not random .
>> it couldn't be a random place? it couldn't be a random time, random anything?
>> it's not random .
>> reporter: but he seemed to know details of the crime that only someone involved would know.
>> so is randy jr . trying to cover his own tracks or somebody else's?
>> i think he's trying to do both.
>> reporter: as investigators continued to focus on things found at the tint shop, including a large burn mark behind it and what looked like burnt scraps of evidence from the crime, randy jr . went out of his way to keep his father out of it, to protect him.
>> he's been a good father. he's really a good man. he's a very hard worker. he's a stand-up guy. he tries to direct me the right way, and i go the wrong way. he would never do nothing like this.
>> honestly, i think you may be involved in it.
>> that's why we've got to clear the air.
>> can i --
>> you know what i mean ?
>> then we've definitely got to clear the air.
>> reporter: detective kendall really suspected randy jr . and one of his buddies had committed the murder.
>> you said you need some money, quick money. you're desperate.
>> all right.
>> you're high on crack.
>> you confront the people at the house because you think they're going to have money. things get a little out of control.
>> all right.
>> and someone ends up being stabbed.
>> okay. you say --
>> reporter: then the detective pulled out the heavy artillery. he tried to crack randy jr . by telling him his own father thought he did it.
>> everything you [ bleep ] said has been a lie. your dad's out there crying.
>> why is my dad crying?
>> because of what you did. come on, dude. i feel bad for your dad.
>> reporter: if police thought they had this case solved, if they thought randy jr . and a drug buddy had committed this crime, they were in for a shock. thanks to a most unusual informant. randy jr .'s