The girlfriend jumped on the deputy's back and started choking the deputy (deputy now had to deal with two persons).
The girlfriend said: "We will kill him!" referring to the deputy.
One handcuff was on the man (Dejuan) but it was so badly damaged in the scuffle that it had to be removed with tools from the dead body.
The woman attempted to grab the Deputy's gun.
The Deputy was injured and had to treated at a hospital.
I assume at this point the Deputy feared for his life
The Deputy shot and killed Dejuan Guillory to extricate himself from this deadly encounter. Note the girlfriend was choking and trying to take the gun away from the Deputy and Dejuan had previously hit the Deputy to knock the Deputy to the ground.
The LIBERAL (dingbat) media is claiming the Deputy wrongly shot the man.
It is possible that the Deputy had a mild concussion from the events that ensued.