This is a long article so I'm going to grab some pieces of it, click the link at the bottom for full disclosure:

"Prior research has found that many officers involved in shootings suffer from “postshooting trauma”—a form of posttraumatic stress disorder that may include guilt, depression, and even suicidal thoughts."

Table 1. Officers’ perceptual distortions during shooting incidents (n = 113)
Distortion	At any time	Prior to firing	Upon firing
Tunnel vision	51%	31%	27%
Heightened visual detail	56%	37%	35%
Both visual distortions	15%	10%	11%
Auditory blunting	82%	42%	70%
Auditory acuity	20%	10%	5%
Both aural distortions	9%	0%	9%
Slow motion	56%	43%	40%
Fast motion	23%	12%	17%
Both time distortions	2%	0%	2%
Other	13%	6%	9%
Total	95%	88%	94%

Table 2. Officers’ responses following a shooting
Physical response	At any time (n = 113)	First 24 hours (n = 112)	First week (n = 113)	Within 3 months (n = 111)	After 3 months (n = 105)
Trouble sleeping	48%	46%	36%	16%	11%
Fatigue	46%	39%	26%	7%	5%
Crying	24%	17%	7%	2%	2%
Appetite loss	17%	16%	8%	2%	1%
Headache	7%	6%	4%	1%	1%
Nausea	4%	4%	4%	0%	0%
Other physical response	19%	18%	11%	12%	6%
Thoughts and feelings
Recurrent thoughts	83%	82%	74%	52%	37%
Anxiety	40%	37%	28%	13%	10%
Fear of legal or administrative problems	34%	31%	25%	19%	11%
Elation	29%	26%	19%	11%	5%
Sadness	26%	18%	17%	5%	5%
Numbness	20%	18%	7%	4%	3%
Nightmares	18%	13%	13%	10%	6%
Fear for safety	18%	9%	10%	9%	8%
Guilt	12%	10%	5%	6%	2%
Other thoughts or feelings	42%	33%	23%	20%	14%

"Several officers indicated in interviews that they thought something might be wrong with them because they did not experience the symptoms that training taught them to expect; others felt that, through the power of suggestion, their reactions were more severe than they would have been otherwise."
"Most officers who held this opinion said they believed their department required counseling to shield itself from legal liability, not to help the officers themselves. They stated that they did not talk frankly to the counselors because they did not trust them to keep the sessions confidential; in some cases, they thought the counselors were incompetent."

full article here