SAN MARCOS, Texas -- San Marcos investigators are trying to figure out who killed Robert Lee Casteneda early Monday morning.

A makeshift memorial now sits where the victim's body was found.

Commander Kelly Bomersbach said her team rarely responds to a call at Twin Lakes, off Hunter Road in San Marcos.

"It's relatively quiet, maybe just some loud music disturbance calls from time to time, but nothing of this violent nature," said Bomersbach.  

Neighbors are keeping to themselves and didn't want to speak on camera, but said Castendeda has small children. Police confirmed the children were not home at the time of the shooting and they were with their mother.

Pam Cripple lives one complex over. She said she heard the commotion Monday and wondered what was going on so early in the morning.

"I walk through this place almost every day, catching the bus or going over to the shopping center. And it just seems like a really peaceful place, people, if I see them getting out of the cars, they'll smile and say hi to you. It's just unbelievable, I'm just shocked," said Cripple.  

Police still don't know who shot and killed Casteneda.

"At this point it's still a very active investigation, we've done some search warrants on some vehichles, we're talking to neighbors, any potential witnesses, and trying to track down any leads that we have. It's very active," said Bomersbach.  

Bomersbach said this is the city's fourth murder of 2017. Anyone with any information on Casteneda's murder is asked to call the San Marcos Police Department at 512-753-2108.