"Once we start to get beyond two days, [suspects] are enlisting help and hiding evidence," Farr, a member of the Denver Traffic Operations Bureau, said.
It's why he will be the first to admit that it's critical to get a good lead early on.
It's likely a big part of the reasoning behind the "Medina Alert" that was issued on Monday night shortly after someone driving a white van hit and killed James Garcia as he was trying to cross Sheridan.
The Medina Alert is named after Jose Medina, a young valet who was hit and killed while he was parking cars outside a Denver nightclub early last year. The driver was eventually apprehended after a cab driver jotted down key information related to the truck in question.
On Monday, taxi companies and members of the media were alerted to the hit-and-run at Sheridan and Colfax with the help of the Medina Alert.
Denver Police say they're looking for a white, 90s model GMC Safari van. It should also have front-end damage to its grill and will also be missing the letters "GMC" on the front.
Linda Limon is Jose Medina's mother. She says on Wednesday she will honor what would have been her son's 23rd birthday.
"It's very heart breaking to know that somebody can actually hit another human being and just leave them like they were nobody," she told 9NEWS via phone.
She says she was deeply encouraged by the use of the Medina Alert on Monday and hopes it will eventually lead to an arrest.
Denver Police spokesperson Sonny Jackson feels the same way.
"It's key that we try to talk to everyone right away in order to see what they remember when it's still fresh in their minds," he said.
Jackson says it's important to note that the driver of the white van was likely not at fault at first.
"It sounds like the van had the right of way and that pedestrian wasn't necessarily in the cross walk area," he said.
Farr also says the pedestrian was walking against the light.
But the moment the driver took off, the case became a serious criminal investigation.
"State law requires everyone involved in a crash to remain at the scene," he said.
9NEWS wanted to provide information on other unsolved hit-and-run cases. Those cases are listed below.
Unsolved hit-and-runs from the Denver Police Department:
May 6, 2011: At 5:17 a.m. case 11-211024: A bicyclist making his way into work was struck by a large vehicle and died as a result. The scene evidence strongly suggests a tractor-trailer combination. No eye witnesses or video from area business.
Sept. 25, 2011, 03:32 a.m. case 11428653: A pedestrian attempting to cross Interstate 25 was struck by several vehicles.
Oct. 15, 2011, 03:33 a.m. case 11-459273: A vehicle eluding a police officer left the roadway and ran over a transient sleeping in a stand of trees. The driver fled on foot and has not been identified.
Jan. 15, 2012, 9:37 p.m. case 12-20293: This case is currently open and the accident report is not available. The pedestrian, Ramon Diaz-Lozano was killed as he crossed the street mid-block and was struck by a northbound vehicle on Federal Boulevard near Kentucky Avenue. A white Honda Accord was recovered abandoned nearby with fresh damage and the occupants fled on foot.
Unsolved hit-and-runs from the Aurora Police Department:
Dec. 15, 2009, 9:45 p.m. case number 2009-50468: Frank Correra was walking north across East Alameda Avenue just west of Potomac. He was not using the crosswalk and was crossed against the green signal for eastbound traffic. Police believe a Saturn was in the far right lane and an SUV was in the middle lane traveling eastbound. The Saturn driver saw Correra and began slowing to avoid hitting him. The SUV did not slow and Correra was struck by the SUV. The SUV then fled the scene. Debris from the SUV was matched to an 2005-2006 black Jeep Grand Cherokee. Police did not receive the correct lead to vehicle and driver. The case remains unsolved and inactive.
Dec. 16, 2009, 6:10 p.m. case number 2010-46900: Keino Taylor and a friend had responded to assist a family friend when their car broke down on Pena Boulevard just east of the off-ramp from westbound Interstate 70 to Chambers Road. Taylor arrived in his Chevy Suburban to tow the broken down Dodge Durango from the side of the road. After Taylor got out of his car, he was struck by an unknown vehicle that had drifted off of the side of the road. Taylor jumped up and was able to clear most of his body from the path of the vehicle. His lower leg became pinned between the two cars. The momentum flung him to the front of his Suburban. The vehicle that struck him continued westbound on Pena leaving the scene. Taylor survived but ultimately lost his lower leg due to the injuries. Despite the number of vehicles in the area, no one reported seeing the at-fault vehicle and we never received a good description of the driver or the car. The case remains open but inactive.
Jan. 30, 2012, 2:30 a.m. case number 2011-3794: Royce Wallace was walking across Havana Street when he was struck by a vehicle that fled the scene. A passerby found Wallace in the street after the hit-and-run vehicle left the area. Wallace was transported from the scene but later died. Police received some tips but were never able to locate the vehicle. The case remains open but inactive.
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