LAS VEGAS (FOX5) -

Two Las Vegas teens accused of drowning a pair of kittens will spend the weekend behind bars. On Friday, a judge ordered the 16-year-olds to undergo a psychological evaluation.

For the second time in as many days, the pair appeared separately in juvenile court. This time, it is over concerns of what might happen if the teens go free.

"The boys thought they were doing what's correct, and they humanely euthanized the kittens," Juvenile Probation Officer Teresa Wicks told the court.

She added that after interviewing the father of one boy, that he not only condoned their actions, but justified them.

A neighbor captured two photos of the teens after they allegedly drowned two kittens in a cup of water, using a barbecue tool to hold one kitten down.

"The way they went about handling this … was it appropriate? No," said Tom Erickson, an attorney for one of the teens.

He told the judge that his client was worried the mother cat would abandon her kittens, or that they would starve and die in the heat.

Animal cruelty became a felony in this state last year, and this is the first case where that new law has been applied.

"We have to be very careful of those types of individuals," said psychologist Louis Mortillaro, who adds that if this type of behavior is not stopped early, then it tends to repeat itself and get more violent.

"Some parents do believe that it is permissible to drown unwanted animals and I've seen this in my psychology career … then the kids would learn that's okay," Mortillaro said.

FOX5 has made attempts to speak with an adult at the home where the alleged crime happened. A man answered the door, but quickly slammed it shut.

"We need to make sure there's not some larger, underlying issue that needs to be addressed here," argued prosecutor Michael Watson.

Judge William Voy ordered the teens to remain behind bars until a plea hearing Monday morning. After that, he said the teens will undergo a psychological evaluation to determine future risk.

"You're developing sociopathic tendencies, in which case that's extremely serious, because the literature says there's not much you can do to fix that," Voy told attorney Erickson. "I'm not saying that's your client's situation but that's why the system reacts strongly."

John Momot, the attorney for the other boy argued that his client has no prior criminal history and he does well in school. His parents were also by his side in court.

Both teens are expected back in court on Monday for a plea hearing.

Copyright 2012 KVVU (KVVU Broadcasting Corporation). All rights reserved.