Dateline | April 03, 2013
>>> morgan mengel and her young sitting in jail for the murder of morgan 's husband kevin . morgan had confessed to playing a small part in the crime, helping steve shappell come up said, that was taken too far. what were your first impressions of her?
>> very good. i mean, the allegation compared to the person i was speaking to did not seem to fit.
>> reporter: morgan 's attorney jack mcmahon says the case for murder against morgan was weak. she wasn't at the crime scene when kevin was killed and had no convincing motive for wanting her husband dead.
>> in fact, financially she was way worse off with her husband's death than she would have been with him alive because he was the life blood of the company and there was no life insurance .
>> reporter: you think she had musings, i wish my husband wasn't around, i wish someone would take care of it.
>> morgan was walking around with dynamite and these musings and saying it to certain people. and steve shappell was the man who lit that match. somebody took action. and that is steve shappell. he's a cold-blooded killer.
>> reporter: he hardly looked like one when police picked him up in denver and got him into the interrogation room. he was meek, his voice was quiet and shaky with fear. district attorney pat carmody.
>> he admitted the whole crime. he said he was in love with this woman and he thought this was the way to get her forever.
>> reporter: steve said morgan was not kidding when she came up with the plan to kill kevin .
>> she wanted him dead. and she wanted to be with me forever.
>> reporter: and steve said that after the murder, far from being scared, morgan was grateful.
>> she asked me if i was all right and kissing me. she came back with water and began like rinsing off the area writ happened.
>> reporter: which is why the garage looked so clean when employees arrived for work that monday morning after kevin 's so-called departure.
>> walks in the garage, steps over her dead husband, kisses shappell and says let's get a tarp and start cleaning the scene.
>> reporter: they were pointing fingers at each other over who really planned the murder. and the d.a.? he believed steve . he offered him a lesser charge of murder to testify against morgan and charged morgan with premeditated murder . a mandatory life sentence .
>> i think she found the most gullible person she could. she used him as a pawn to do her actions. he held the shovel, but morgan held the strings.
>> reporter: you think morgan was in charge of this operation?
>> 100% i believe that. morgan had a way with men, she just did. she had a way with men. and i think the same way that she had my brother, you know, under her spell, she had this kid as well.
>> reporter: and the d.a. says it was morgan herself who had been sending those fake text messages to kevin 's family after the murder, not steve . cell phone tracking records proved it.
>> she's texting kevin 's family assuring them that he's okay, he just wants to be left alone. she's the most evil woman i've dealt with.
>> reporter: morgan mengel went on trial in late january 2012 , a year and a half after kevin mengel had been murdered, but in addition to steve shappell waiting in the wings to testify, the d.a. had something else, something extremely rare in a murder trial. a play by play of the crime courtesy of text messages between morgan and steve as it happened.
>> we were like, holy smokes , there it is. it's right there.
>> reporter: the detectives had discovered the trove of messages during their interrogation when they pulled morgan 's phone records looking for steve .
>> we knew the exact time of death. we knew how it happened. and so we were floored.
>> reporter: the texts are chilling. four hours before the murder morgan texts steve , we ready? she type. steve responds, yep, at the shop now. then a half hour before the murder morgan asked steve about the poison snapple. he drinking it, she asks. steve writes back, yeah, kind of. we're just waiting for him to bend over . i have a shovel in my hand. ha ha . morgan 's response. nice, babe. steve doesn't reply. morgan writes, you backing out?
>> there's a gap there where nothing happens, and she then gives him the final taunt, you backing out? and when she says that, he texts back, it's done, get here now.
>> these text messages don't even seem real. they just don't seem real.
>> reporter: as incriminating as those messages sounded morgan 's defense was ready to press her case in court claiming she was no murderous master mind .
>> i'm not so sure even to today that she had a fully formed belief that stephen shappell was actually going to do this?
>> reporter: but the defense never got a chance. a few days into the trial, a police officer said something on the stand, hearsay that could prejudice the jury. and the judge sent everyone home.
>> chester county judge declares a mistrial in a love triangle murder case.
>> reporter: for kevin 's family, the delay was torture. more waiting for answers to questions they never wanted to ask.
>> i wanted to know if he knew it was happening. i wanted to know if he begged.
>> reporter: why did you want to know?
>> kevin was so sweet and kind, and i know he must have been so, so scared.
>> reporter: the story of those final moments could only be told by steve shappell. but even from jail, as they awaited their fates, morgan was trying to keep him quiet. she wrote him a letter saying she had given birth to his twins. so her game plan was if he thinks we have kids together, he won't rat me out.
>> he would ask have you figured out ho has a better chance to get out of here? i need to raise our children.
>> reporter: except it was another lie. another manipulation. this past february, the prosecution and defense were back at the chester county courthouse for morgan mengel's retrial. steve was set to testify, but then another surprise. the day the testimony was set to begin, morgan stopped the trial from happening and changed her plea. she admitted to first degree premeditated murder . even her own attorney was stunned.
>> i believe morgan saw the handwriting on the wall . she realizes that whatever action she took, it resulted in his death and resulted in shappell killing him.
>> reporter: steve was sentenced to 40 to 80 years, and morgan life without parole . for the mengel family, now raising kevin and morgan 's children, there is finally some justice, they say, in knowing morgan will remain behind bars forever.
>> i want her to be in jail for the rest of her life. i want her to know that i'm going to be there when her daughter walks down the aisle. i'm going to be there when her daughter had a baby. i'm going to be there with her sons when they meet their wives and graduate from high school .