Crowder told reporters following Sunday's 26-10 loss at Baltimore that McClain spat in his face during an argument on the field.
"I have enough evidence," Sparano said. "It's upsetting to me."
Director of football operations Merton Hanks was not as convinced as Sparano. After reviewing both the video and reports from the on-field officials, including referee John Parry who was in the immediate vicinity of the two players, Hanks determined there is no conclusive video evidence to support discipline in the matter.
Crowder is widely considered one of the league's foremost trash-talkers, so it was no surprise to see him and McClain facemask to facemask trading taunts during a timeout, with an official trying to separate them.
The video shows the conversation ending when McClain rears his head back before thrusting it forward.
"That's just me talking," McClain said. "You can't see spit coming out of my mouth or anything."
Crowder then waves his left hand in front of his face, as if trying to intercept the spittle, before the players are separated.
Harbaugh found McClain innocent.
"I talked to Le'Ron," Harbaugh said. "I've seen the videotape of it. It didn't happen. I don't believe for one second it happened."
The Associated Press contributed to this report.