There is no surer way to be misinformed than to watch TV news.
This particular measure of police safety - felonious killings - is remarkably lower than a few decades ago. After the 1973 peak of 134 murders, these killings began a relatively steady decline through the mid-1980s, when they initially bottomed out at around 70 a year. Those figures continued slowly downward, such that during the 1990s the average was 64 and in the 2000s lower still at around 48. The high in the past two decades was 79 in 1994, while the low of 41 was very recent - 2008. As a result, we might see increases in killings from time to time simply because of natural year-to-year variations, but you'd have to look all the way back to 1961 to find a lower figure than the 41 in 2008.
Despite attention-grabbing headlines, we also should bear in mind that today there are more than twice as many sworn police officers as there were serving in the early 1970s.