There have been lingering questions about whether the deaths could have been prevented.
Eyewitness News has learned deputies got suspicious the first time they were at the house.
PHOTOS: Scene where 6 children and 2 adults were found dead
Sources say something happened seconds after they knocked on the door that caused them to go back and knock again. However, they still left. And later that day, Dwayne and Valerie Jackson -- along with their six children -- were found shot to death.
Sources tell Eyewitness News that the sheriff's department had enough probable cause to go into the house where David Conley was allegedly terrorizing the entire Jackson family and they say there is a call slip record to prove it.
We previously reported the first welfare check occurred around 10:44am Saturday. Sources say that after deputies knocked on the door, and got no answer, but they heard a deadbolt lock behind them. They knocked again, nobody answered and then they apparently left after asking questions around the neighborhood.
Sources say that information is on the call slip.
"I feel like on the second time maybe something else could have happened. They could have tried to force their way in. Something. They could saved some lives," said neighbor Karen Riggins.
Riggins was among a few dozen people who came together at a candlelight vigil Thursday in the front yard of the home on Falling Oaks Road where the murders happened. Friends and neighbors were there seeking comfort.
"One of the people who was killed was my friend," said Brian McCoy, a classmate of one of the victims.
"We're just trying to give them strength during this time," Harold Hale, a minister who led prayers, said.
A local children's advocate says he cannot believe sheriff deputies did three welfare checks on the house that day, before finally discovering the tragedy.
Randy Burton, of Justice for Children, said, "Why they didn't take action. They could have saved these children's lives. Apparently, they were been held at gunpoint for hours and hours and hours, being terrorized by this man before the murders finally occurred."
Late Thursday, Justice for Children, called on Harris County Judge Ed Emmett to launch an independent investigation into the "complete failure" of the system.
So despite several welfare checks and not finding anything and returning for that awful murder scene, we asked if there is an internal investigation, and the sheriff's department said there is no investigation.
The Harris County Sheriff's Office released this statement this afternoon and the following timeline of calls for service:
The calls for a welfare check were triggered after 911 call takers received reports that a female on the property had sent concerning messages via Facebook and SMS Text to family members in states outside of Texas.
Repeated attempts to make contact with residents inside the Falling Oaks home went unanswered, until visibility changed allowing deputies conducting a perimeter search of the premises to observe the body of a deceased individual inside of the home.
Due to the exigent circumstances observed at 10:26 PM, deputies forced entry into the home, and were immediately met with gunfire.
The Sheriff's High Risk Operations Unit and Hostage Negotiation Team were able to negotiate the peaceful surrender of Conley at approximated 11:58 pm.
The Harris County Sheriff's Office has received permission to release the timeline of events occurring at 2211 Falling Oaks Road on August 8, 2015. In order to preserve the integrity of the criminal investigation and prosecution, certain details have been omitted in accordance to the Texas Public Information Act.
10:42:04 - Call created following request to Harris County 9-1-1 for a welfare check.
10:49:08 - Deputies arrive on scene at 2211 Falling Oaks Road.
11:37:54 - Deputies report 2 vehicles on scene, no response from inside the home, home secured.
12:05:07 - Deputies clear scene.
12:13:51 - 9-1-1 is contacted by rep requesting updated information from scene.
16:31:06 - Call created following request to Harris County 9-1-1 for a welfare check.
16:43:37 - Deputies arrive on scene at 2211 Falling Oaks Road.
16:48:49 - 9-1-1 is contacted by additional rep for welfare check, advised Deputies are on scene.
16:52:00 - Deputies report 2 vehicles on scene, no response from inside the home, home secured.
16:54:13 - Deputies clear scene.
17:36:20 - Call created following request to Harris County 9-1-1 for a welfare check.
18:10:52 - Deputies arrive on scene at 2211 Falling Oaks Road.
18:14:50 - Deputies advise there is no response from inside the home, home secured.
19:51:21 - Call created following request to Harris County 9-1-1 for a welfare check.
20:55:35 - Deputies arrive on scene at 2211 Falling Oaks Road.
22:26:53 - Deputies advise one person down observed inside the house.
22:28:35 - Shots fired by suspect as deputies force entry.
23:58:00 - Suspect in custody.