HOUSTON - Consider the litany of violent crime in just the past week.

A family grieves for a father and son shot dead in a southeast Houston apartment after an argument in a game room. A child finds a mother murdered in her own bed. A woman leaving work is gunned down while begging for her life.

If these heavily publicized violent crimes leave the impression homicide is on the rise in Houston, crime data for the first quarter of this year indicates that's correct.

Between January and March 2015, Houston police reported investigating 73 homicides. That compares to 46 homicides for last year, an increase of 59%

Nonetheless, criminal justice experts caution against jumping to conclusions about crime trends based on such short term data.

"I think it's really hard to read much into a snapshot like that," said Sandra Guerra Thompson, the director of the University of Houston's Criminal Justice Institute.

Homicide numbers have generally been trending downward in recent years, a phenomenon that police and criminologists have credited to variety of factors.

"You know, probably for the last twenty years we've seen a dramatic drop in violent crime here and nationwide," Thompson said.

The decline has been especially noteworthy to longtime Houston homicide investigators, who remember an era when murders happened literally every day. In 1981, during the peak of the city's economic boom, Houston recorded 701 homicides.

A decade ago, in 2005, Houston suffered 334 homicides. In 2011, that number dropped to 198, a tally that surprised even police investigators. So the answer to the question of whether homicides are on the rise or the decline depends upon the time frame.

Exactly why homicide numbers rise and fall has long been a subject of debate in criminal justice circles. Some longtime investigators give much of the credit to modern emergency medicine, which saves the lives of countless victims who would have died in an earlier era. Others cite demographic trends, pointing out that young men are more likely to commit crimes than older people.

"How many children are being born at a certain time can make a difference in terms of crime rates," Thompson said.

Houston's police chief said most homicides happen either inside homes or as a byproduct of some sort of illegal activity. Chief Charles McClelland suggested there isn't much police can do to prevent most homicides.

"There's very little that a Houston police officer can do to intervene in an apartment complex inside somebody's bedroom or somebody's living room when two or three people get into a heated, passionate argument and someone pulls out a gun and kills two or three people."