A 20-year-old Coon Rapids man has been furiously exploiting unlocked houses in his city and burglarizing them, authorities said. Sometimes he'd find that the residents didn't learn their lesson, police noted, and would return and find the houses still unlocked and ripe for thievery.

Suspected of pulling off 15 burglaries and attempting another 30 in recent months, Jacob D. Shultz was charged last week in Anoka County District Court with five counts of first-degree burglary. Shultz was arrested Wednesday and remains jailed in lieu of $100,000 bail.

Some of the crimes occurred while residents were at home, according to the charges. Shultz often stole small amounts of cash and cigarettes, the charges continued.

All of the burglaries occurred at houses where doors were unlocked, often garage service doors or sliding doors leading directly into the houses.

Shultz returned to some of the same unlocked houses over the course of several weeks and struck again, police said. He hit one residence "several times," the charging document read.

"It is so important that people lock their doors," said police Capt. Jon Urquhart. "It only takes a few moments, and it can keep people from becoming an easy target for this type of crime. Lock before you leave or go to sleep; I can't stress it enough."

Police in Coon Rapids say they have been particularly aggressive in investigating burglaries. The city has had a sharp decline in burglary cases over the past several years.

According to the criminal complaint:

About 6:10 a.m. on Feb. 21, barking dogs awoke a man and his son in a house in the 10200 block of Mississippi Blvd. NW. The residents found Shultz in their kitchen and saw him take a wallet, run outside and pedal away on a bicycle. The wallet was found outside, but the $150 in it was gone.

Acting on information from their investigation, police interviewed Shultz early in the morning Wednesday, when he admitted to entering a house in the 2400 block of 103rd Avenue NW "several times and [had] stolen money or attempted to steal money," the complaint read.

Three times, he continued, he entered through an unlocked garage service door, went into the house and took money from a purse on a table. The last time he came to the house, barely an hour before talking to police, he "found the garage service door locked, got scared and ran," the complaint continued.

The earliest burglary he admitted to occurred on Jan. 11, a house on Zion Street NW. Shultz said he burglarized that house three to five times by entering through an unlocked sliding door. There was at least one person home sleeping in each instance.