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Tyshar Mosely says she was trying to protect her kids when she stabbed and killed her ex -boyfriend, Aymn Brown, last Thursday. Police did not charge Mosely with murder, instead saying she acted in self-defense.

Aisha Cash says there had to be something more, something buried deep inside Tyshar Mosely that lead to her to kill.

“The energy she took to stab him she could have got out of the situation she didn`t have to stab him and kill my brother,” says Cash, the victim’s sister – in – law.

Cash admits her brother – in - law, Aymn brown, wasn't perfect and that he and his ex - girlfriend fought often. Cash says he loved kids would never do anything to harm Mosely's.

Cash says, “I was able to take it you know… domestic violence and all that but when she said she was protecting her kids that was the last straw.”

However, whether or not Mosely was protecting her kids, police say there are a lot of gray areas when it comes to claiming self-defense.

“There’s no definitive line when it comes to self-defense. Self-defense is a common sense thing. Everybody knows within themselves what self-defense is and what it is not,” says Sgt. Daniel Blom.

Sgt. Blom says fatal self-defense cases are rare but there is a check list on how police decide whether or not to agree with a self-defense claim.

“The things that are taken into consideration by either witnesses or the person themselves and then comparing that with the evidence found at the scene to see if it matches up with those statements,” says Blom.

Additional factors like a violent past and even the size of the people involved can sway a decision.

Beyond the physically of it all, family members want to know what Mosely was thinking, forcing them to move forward.

“Why would you think that would be the resolution for anything? You get to walk away and get your kids but you affected so many people.”