KILLINGS RISE WITH MERCURY.

Byline: Jesse Hiestand Daily News Staff Writer

A four-day string of 100-degree-plus temperatures has led to an ugly side effect: the homicide rate has more than tripled in the heat.

While the total number of slayings in Los Angeles continues to plummet, from an average of nearly two a day in 1996 to little more than one a day now, there have been 15 homicides in the city - three of them in the Valley - since the heat wave started Friday.

Police said Tuesday that the blast-furnace daytime temperatures and sweltering nights are a leading contributor to the rise in killings, just as crime of all types tends to increase in the sizzling days of summer.

``During the hot months, almost all of these people are drinking and usually tempers flare or they get some liquid courage and go out and do what they got to do,'' said homicide Detective Frank Bishop of the Los Angeles Police Department's Foothill Division.

Bishop and other detectives spent Tuesday interviewing a possible suspect in the killing Monday of Sylmar resident Jerry Jordan, 30. The suspect was released because he could not be linked to the slaying, which was gang-related and alcohol-fueled, Bishop said.

The motive for the shooting was believed to be a personal dispute involving Jordan and the three men in their 20s who parked a Dodge van in a driveway in the 15400 block of El Cajon Street and opened fire when Jordan walked up to the driver, he said.

Homicide detectives from the Devonshire Division spent Sunday night investigating a drive-by shooting in North Hills that claimed the life of Salvador Saldana, 23.

``Historically, with warmer weather, for some reason we have more incidents,'' said Foothill Detective Mike Oppelt. ``All I know is I got out there at 2 in the morning and it was 80 degrees and it stayed hot all night. It got up to 90 degrees at 9 a.m.''

The LAPD's Central Bureau, which patrols downtown and Eastside neighborhoods, led this deadly increase with five homicides in the past few days, three of which were gang-related.

``Actually, I was surprised last weekend that we didn't have more than we did because it was real hot,'' said South Bureau Detective John Karle.

``Heat brings people out and when you have more interaction, you're going to get disagreements and some aren't handled in the most civilized manner. That winds up in a spike in that type of activity.''

Police officials say this seasonal hike in crime should fade when the weather cools. In the meantime, they remain encouraged by a 28 percent decline in homicides, to 273 as of midnight Saturday from 381 by that time last year.

According to FBI figures, Los Angeles had 709 homicides two years ago, for an average of about 1.9 per day and is now on track to have about 400 this year, at the current rate of about 1.1 per day.