Video Evidence 101
Network surveillance cameras help Green Bay schools hone their C.S.I. skills
- By Fredrik Nilsson
- Jan 01, 2013
Public schools may not be a hotbed of criminal
activity, but they do have their share of incidents
on campus that need to be investigated. Green
Bay Area Public School District, the fourth-largest
school district in Wisconsin, had been using
analog surveillance technology as part of its
investigative toolbox for 12 years. But with
24-hour-a-day operation, the multi-school CCTV
system had far exceeded its useful life.
With 38 primary and secondary schools spread across 92 square
miles, the district needed to upgrade surveillance to better protect its
21,000 students. It was time to search for a replacement solution that
not only gave each school the autonomy to view its own video but
would also allow the district the flexibility to manage and support the
Allen Behnke, directory of safety, security and telecom for the
school district, decided to retire the old, disparate analog systems and
start fresh, reasoning that the advances in digital surveillance technology
would easily justify the investment—not only in superior image
quality but also ease of use and remote maintenance.
“Initially, we thought we would simply add encoders to the analog
cameras to connect them to the LAN/WAN the district already had in
place,” Behnke said. “But when we looked at all the advances that digital
megapixel technology offered us, it just made sense to scrap the old
system and start anew.”
The district worked with SimplexGrinnell, a Tyco business, to
design a new system that would replace the old analog CCTV equipment
with more than 500 Axis Communications HDTV-quality, fixeddome
network cameras controlled by a Video Insight Digital Video
Management System (VMS).
Video Insight includes intuitive map and floor plan navigation features that allow administrators to view and
clip video from their respective schools,
either via their desktop computers using
Monitor Station or the Web Client or remotely
from iPads and smartphones, while patrolling
“Video Insight’s open architecture, ease of
use and features that were developed specifically
for large systems with multi-campuses
and facilities is what made it best-suited for
a project such as the Green Bay Area School
District,” said James Whitcomb, Video
The network-based solution was then configured
to store video locally at all the secondary
schools. For the elementary schools,
depending on location, the video streams to
central servers on either the east or west side
of the district. The school district’s security
department maintains full access to all the
video servers and cameras, allowing technical
staff to adjust camera parameters remotely
and update camera firmware globally, avoiding
the cost and delay of onsite service calls.
Providing a Better
Class of Coverage
While the district’s legacy systems included a
mix of analog PTZ and fixed cameras, SimplexGrinnell
calculated that replacing them
with megapixel fixed-dome network cameras
would provide Green Bay campuses with
greater coverage. Martin Security Systems, a
Wisconsin-based provider of “simplified
security systems,” was then contracted to
install the IP cameras.
“These newer fixed-dome cameras cover
what three of our old [analog] PTZ cameras
used to do,” Behnke said. “Part of it is smarter
camera placement, but most of the improvement
is because these new cameras provide a
higher resolution and greater density of pixels
as well as a wider field of view.”
Behnke feels that the megapixel fixeddome
cameras are a much better deterrent
than the district’s analog PTZ cameras
because “if a student is thinking about doing
mischief, they can’t tell which direction the
camera is pointing. Plus, you avoid the problem
of the PTZ camera being pointed in one
direction when the real event is happening in
the opposite direction.”
The outdoor-ready, 1080p HDTV and
5-megapixel network cameras installed on
building exteriors and in school parking lots
include automatic day/night features and
tampering alarms to ensure uncompromising
coverage around the clock. The low-profile
footprint of the fixed-dome cameras
keeps their presence unobtrusive, which was
key for a welcoming educational atmosphere.
Additionally, the cameras’ high-tolow
temperature thresholds and auto-iris
control easily accommodate the extreme
glare coming off of ice and snow, which is
typical of Wisconsin winters.
For interior locations such as hallways,
common areas and known hot spots, the district
uses 1-megapixel network cameras that
also feature automatic day/night operation
and tampering alarms.
Many of the cameras are connected to the
district’s network via Cat-5 and Cat-6 cabling,
except for a few locations such as the back
ends of parking lots where the system was
augmented with wireless technology to avoid
the expense of trenching a fiber line to the site.
Evidence under a Single
The switch from analog to IP-based surveillance
gave district administrators a host of
investigative options they never had with
their old system.
“Being able to intelligently search the video
from the end user’s desktop is huge for us,”
Under their legacy system, users had to go
into the server room and sift through hours of
footage to find the video they needed.
Remote maintenance was another big plus.
“With our old system, we had to physically
go right to the camera to do any adjustments,”
Behnke said. “But with the Axis cameras
residing on the network, we can log into the
surveillance system to troubleshoot, refocus
and adjust camera parameters remotely. We
can pretty much put a camera in place and
never physically touch it again.”
At the end of the day, however, it was the
image clarity that really sold the district on its
new network surveillance system. Administrators
can zoom in on archived images to
extract greater forensic detail than was possible
with the previous system. Put another way,
the HDTV video they pull from today’s fixed
IP cameras provides more usable pixels than
the old analog PTZs, even if the camera was
zoomed in. In one specific case of an attempted
break-in, even though the perpetrator’s
face was hidden from the new HDTV cameras,
local police were able to apprehend the person because his distinctive clothing, backpack and gait were clearly
detailed on the video.
Securing the Chain of Evidence
Because the district opted for a distributed storage configuration,
Behnke’s team takes utmost care to keep the video archives secure.
Leveraging the video management system’s directory feature to control
access to the system, Behnke strictly limits principals, associate principals
and school resource officers to live and archived viewing of their
own respective campuses. In case of emergency, local police are granted
similar controlled access. But if someone needs a copy of a particular
clip, he or she can receive it only through Behnke’s department.
“For our own protection, we limit the number of people who can
export video to an external device,” Behnke said. “It only takes a matter
of seconds for something to go viral and create havoc with our district’s
reputation, so we restrict that feature to our security technicians only.”
Separating the Guilty from the Innocent
Though the cameras are primarily used for forensic investigation,
administrators monitor the cameras live from their office desktops or
mobile devices as they walk the corridors of the school.
“Because we have secure login credentials to Wi-Fi throughout the
district, the principals, associate principals and school resource officers
don’t have to be chained to their desks to see what’s going on in
another part of the building,” Behnke said.
Both the wireless connection and video streams also have the highest
level of logical security built in such as HTTPS encryption, IP filtering
and IEEE 802.1x.
As an experienced user of the new IP surveillance system, Curt
Julian, associate principal of East High School, finds that having video
evidence to support the information he gathers during an investigation
helps him and his colleagues determine what really transpired.
“We try to use the network cameras as corroborative tools rather
than the sole source of evidence,” Julian said. “But there have been
times that the cameras were the only way to determine the true nature
of an event.”
In one case, the video revealed that a student had been wrongly
accused of pulling a fire alarm immediately before a school concert. The
real culprit turned out to be a staff member feeling around for the light
switch in a dark gym and pulling the alarm by mistake.
In another case, a student was suspected of stealing a beverage from
the cafeteria cooler. The video archives revealed that the student had
mastered his pilfering technique by stealing bottles every day for more
than a month prior to the day he got caught. Not anymore, thanks to
the high-quality video evidence.
During a more serious incident, more than 50 students were present
during a large fight in a school hallway. Witness statements conflicted
as to who the participants were and who were simply bystanders.
Because the fight would likely lead to expulsion hearings, it was imperative
to establish the true facts of the incident.
“The video evidence allowed us to corroborate statements and weed
out the truth from the lies and misperceptions,” Julian said. “Without
the footage, we’d never have broken the code of silence that persisted
among the actual participants. We eventually learned that the fight
stemmed from a verbal confrontation that took place days earlier. We
searched the video archives and were able to document which students
were involved from the start.”
“We may not be quite C.S.I. caliber,” Behnke said, “but the speed at
which we can search and retrieve video and the quality of images we
capture are just phenomenal.”
This article originally appeared in the January 2013 issue of Security Today.
Fredrik Nilsson is the VP, Americas, for Axis Communications, Inc. He has more than 15 years of experience with IP video systems and is the author of “Intelligent Network Video: Understanding Modern Video Surveillance Systems” published by CRC Press and now available in its second edition.