Authorities in Kern County, California are defending themselves against criticism for confiscating cell phone video of seven sheriff's deputies' fatal encounter with a 33-year-old man.

"For us not to go get videos that are evidence, we wouldn't be doing a very good investigation," Sheriff Donny Youngblood told CNN.

But witnesses to the May 8 incident involving the deputies and 33-year-old David Silva said deputies overstepped their bounds in gathering that evidence.

"They used more force than was needed," said Melissa Quair. "I told them that they didn't have permission to say who could go in or out of my house."

Quair told the Bakersfield Californian that two detectives entered her apartment to seize video taken by her boyfriend and blocked the entrance. Those same detectives, she said, also demanded her mother's phone.

"My mom is disabled and has a lot of doctor and medical numbers stored in her phone," Quair said. "But the detectives didn't care and they told my mom to write all her contacts down on a piece of paper and while she did they watched her like hawks."

Authorities said their run-in with Silva began when a deputy responded to a report of a "possibly intoxicated man" laying on the ground near Kern Medical Center in Bakersfield. Six other deputies, along with two California Highway Patrol (CHP) officers, later arrived for backup. Deputies said Silva began fighting them.

"The guy was laying on the floor and eight sheriffs ran up and started beating him up with sticks," a witness said in a call to a 911 dispatcher. "The man is dead laying right here, right now."

Silva was pronounced dead less than an hour after the encounter.

"It makes it look like a cover-up," Cohn told the Los Angeles Times. "What we're all concerned about is, 'Are these videos going to be altered? Are they going to be deleted?'"

KBAK-TV reported on Monday that another witness gave the family surveillance footage taken near the site of the encounter that shows deputies hitting Silva with their nightsticks.

"Constant bashing, this is constant bashing," said his brother, Chris Silva, while watching the footage. "You can count, you know -- I can't keep track. And it hurts my heart looking at this."

Younglood said that he has asked the Bakersfield Police Department to review the cell phone video to guard against conflict of interest. Officials with the highway patrol refused to comment on the investigation. Meanwhile, sheriff's officials said the seven deputies involved in the incident will not be placed on administrative leave.

Watch CNN's report on the case, posted online on Tuesday, below.