Yes, by a lot. In 2014, 117 police officers died in the line of duty. Of these, at most 76 were killed by felons (assuming 100% of those struck by cars and 100% of those who died because of physical-related incidents qualify as killed by felons - clearly, many don't, since those categories include cops hit while directing traffic, and those who had a heart attack while on duty, for example).

Roughly 140 cops kill themselves every year, so at least 2x the number killed by felons.

That being said, police officer suicide rates (about 17 per 100k population) aren't actually that high when you consider that cops are disproportionately white males 30-60 with access to firearms, a group with just about the highest suicide rates in the country.

http://www.badgeoflife.com/currentmyths.php
http://www.nleomf.org/facts/officer-...ta/causes.html