please, please shawn. reporter: one night crystal captured something horrible. she said it was audio of her husband raping her. you re choking me. you re choking me. please! she walked in, and she was visibly shaken. i knew somethin had happened. reporter: crystal played a bit of the tape for weldon. i ve always been a very protective person. if you re a friend or family, i ll do anything for you. i really wanted to go and kill him. reporter: crystal later called police and had her husband arrested. when he made bail, she called weldon, who came to her house and helped crystal figure out the safest places to hide if her husband returned. checked out the entire house, top to bottom. told her some defensible spaces. reporter: crystal never did need to use her new gun. her husband was convicted of a forcible sex crime and served more than three years in prison. but she was grateful for the
reporter: from an early age, weldon mcdavid was passionate about protecting other people. i i used to protect my friends on the way home from school. we had a bully that tried and tried to start fights with us. and then i found out that a nicely applied arm lock would get that bully to kiss the street. and we didn t have to run from him anymore. reporter: when he grew up, weldon enlisted in the marine corps. after leaving the service, he worked as a firearms instructor. we met weldon back in 2013 when we covered the story of another woman he met at the shooting range. a customer walked in. and i could tell somethin was wrong with her. i i couldn t tell exactly what, but i i could read that she was under some kind of stress. reporter: her name was crystal harris. he s, like, yeah, can i help you. i said, i need to buy a gun. and i said, and it s not just for putting it away. i said, my life is in danger. and it s it s from my husband.
sense of empowerment, and protection, weldon mcdavid gave her. he helped me so much. it s a very unlikely friendship. right, but if i needed him if i was worried about something or whatever i could just call him. reporter: crystal embarked on her new life without her husband. and weldon moved on, too. a few years after befriending crystal, weldon found romance when he met a woman named lea conant. i had decided to learn how to shoot and buy a firearm and learn how to use it i was tired of feeling vulnerable as a woman and being scared of noises at night. reporter: lea said weldon didn t make a huge first impression when he rang up her purchases at the shooting range. but soon she realized. he was interested. and i was not at first. and he won me over. so how did he do that? he s very witty.
reporter: crystal, a mother of two young sons, told weldon her husband was violent and abusive. she said she wanted to buy a gun for protection. so at that point, i asked her, are you prepared to kill him? because that is a very real possibility. you know, if it s his life, your son s life, or your life, then you have to make that decision. and after a few moments, she said, yes, if i have to. reporter: weldon took crystal under his wing, taught her to defend herself even in stressful situations. this guy sounds like he was actually looking out for you a little bit? yeah. somebody who s in the business of saving lives and, you know a warrior and a hero and that type of mentality, yeah, he wanted to help me. reporter: at home, crystal also helped herself, used a mini cassette recorder to gather evidence against her husband. oh, god. stop. please,
and the prosecutor said, that was where weldon came in, the self styled protector. a man prime to react to the exact type of allegations diana was making. oh, god! remember what he said on dateline, when he hear the recording of had husband s abuse? i wanted to really go and kill him. reporter: she viewed weldon as a way to get rid of greg. she saw in weldon the exact kind of person that she d need to carry it out. and it is somebody who has a hero complex. and she needed somebody that she could manipulate. reporter: the prosecutor learned something else. diana admitted that she had slept with weldon. she used her sexuality to get him to do what it is that she wanted him to do. reporter: on september 12th. 2016. weldon mcdavid, and diana lovejoy, were arraigned on