Police are still not sure what lies behind the killing of the two children, whose bodies were found on the outskirts of Guatemala City, or whether they are linked to the murders of two women in the capital on the same day.

The widespread coverage of the story has detailed Guatemala’s long history of violence, much of it rooted in a brutal 36-year civil war which came to an end in 1996. Amnesty International has demanded an end to the “national scandal” of unsolved murders of women and girls in the country.

Amid the gloom, it is worth pointing out some important context: appalling crimes such as this are becoming less common. In 2009 Guatemala saw 46.3 murders per 100,000 people, according to the UN. In 2010 the rate fell to 41.4, and in 2011 it dropped again, to 38.5. And last year it declined for a third consecutive year, to 34.2. This adds up to a reduction of more than a quarter in three years.

What of the murders of women? They have been falling at about the same rate. According to Amnesty there were 695 murders of women in 2010, 631 in 2011 and 560 last year. It would be premature to call this a trend. But it also seems odd to say, as Amnesty does, that there has been “no let-up” in killings of women and girls. In fact, the numbers have dropped by a fifth in the past two years.

The media has always been much better at covering bad news than good, from Guatemala to Britain. This is no bad thing: cases such as the dreadful killings last week deserve every column-inch that they are getting, as without this kind of pressure, the government would have less reason to make things better. But unglamorous good news is worth reporting too, not least so that voters know which policies are working. Beyond the horror of Guatemala’s latest killings is a more important story: outrages such as this are quietly becoming less common.