Digital Media Forensics – Preparation and Presentation at Trial

trial preparation I recently testified in one of the most involved, and important, cases of my career. I was confident in my testimony because my client lawyer and I spent time preparing and rehearsing my testimony. While waiting two days for my turn to testify, I continued to review my investigative notes, and all other work products I created. At that point, I was completely familiar with my findings, all reports and materials used for the case.

The day before I testified, I discovered the only way to access the video projector and sound
system in the court room was through a downloadable software program created by Epson. This software was something I had never encountered for playback in the courtroom. An important detail that my client attorney had not mentioned to me as he knew about it prior to the trial. I had no idea; this was a first for me. In hindsight, it was my job to investigate sooner. Even as an Audio and Video Forensic expert, on site learning objectives can be troublesome, especially when your head is so far into preparation for a expert witness testimony. Lesson learned.

My client attorney forwarded the information from the A/V department of the court, which was a link to download the software program. They asked what operating system I was using and I told them Windows 7. He forwarded the link and I downloaded a zipped file. He told me to meet him at court at 8 AM the following morning, which I did.

I arrived the next morning, met the tech, and he instructed me on how to properly install the software within my Windows 7, Asus Laptop. He told me he was not allowed to touch my laptop. As an Audio and Video Forensic expert, I have extensive experience with technical issues experienced on a computer, but this was a very difficult process.

We launched the program and connected my laptop to the projector. My desktop was now viewable and I took a sigh of relief. Then I discovered none of the forensic applications I use while presenting my investigations in court– Adobe Audition, Premiere Pro and Sony SoundForge – would open. One of the first skills I learned firsthand in the technical support department was that if something isn’t functioning correctly on a computer, go back one step and reverse the most recent changes made to it.

So I informed the judge I was not ready, and the lawyers decided to proceed with some other portion of the trial while I troubleshot the issue. Court began, the jury was brought in, and I unplugged my laptop and snuck back out into the hall. The representative from the AV Company was going to leave and I asked that he stay just in case. He agreed and for the next half hour I began to make my steps back to square one. That’s when we realized: the Epson software assumed ownership over my Sound & Video Card so that it could operate the projector, leaving all of my normal forensic display functions inoperable.

After the last bit of junk was removed we re-booted my laptop and everything worked. I was relieved, until I realized: I didn’t have a projector. I looked at the tech and asked if there was an HDMI input that we could run a long cable to. He said yes, but we would need a ladder and a long cable, which he did not have. He remembered he had a small data projector in his truck. We tested it in the hall and it worked.

Next, we had no cart to put the projector on. We noticed a small antique table that was holding a pitcher of water and some cups in the hallway. This was a very old, historic courthouse, built in 1847. I bet that table had been there for a very long time, because when I moved it the legs were wobbly and the judge – very sternly, almost scolding – told me to lift the table when moving it.

I put the projector on the table, got it positioned, and moved the lectern close as the VGA cable was only 6 feet long. The jury had taken a break and the judge was really rushing me into being ready.

As if this wasn’t enough stress, the prosecutor came over to me and started asking me questions, and ‘my’ attorney was out of the room. She was definitely out of line, and if I would have said anything, Lord knows what would have happened. So I told her I was not able to talk to her. She was very emphatic about wanting to know certain aspects of my investigation that were well covered in my reports. I ignored her and finished setting up as we heard ‘all rise’ and it was just one of those moments that you close your eyes and ask God to help make sure it all works. Everything came on and I remember hearing my ‘boot alert’ on my computer chime through the speakers, and I breathed a sigh of relief as I saw my desktop on the projector screen.

As digital media forensic experts, it is our responsibility to test all presentation tools (software, hardware, images) before testifying in court. These tools help judges and juries understand the facts about our investigation more effectively instead of using just words and reports.

Even though I was told by my client lawyer prior to testifying that the court had a data projector and sound system, it is ultimately my responsibility as the expert to test everything in advance to avoid any technical glitches. That way I would have plenty of notice about introducing an unexpected piece of software (that completely took over my computer) well in advance, instead of minutes before testifying. Interruptions of the technical variety have the potential of distracting us more than the unexpected off the wall questions of a prosecutor.

I chose to publish this blog post so that lawyers and forensic experts understand the importance of technology in the court. I also wanted to share my experience with problem solving in case you are challenged with a similar technological glitch prior to testifying. Stay calm and think logically in order to stay focused and get the job done.


 photo credit: Historic 9th District Court of Appeals via photopin (license)

It’s Important to Know Who Cried for Help

Trayvon MartinAfter spending nearly a full week listening to the Trayvon Martin 911 calls, it has become even more apparent to me why the cries for help are so important. Those cries bring up questions from a forensic perspective that would help solve the case if they were answered. Since the voice is not Zimmerman’s, whose was it? Were there any other people at the scene of the crime that we do not know about? If not, then by process of elimination, we know who was yelling for help. The people in the neighborhood were too fearful to go outside as heard in the other 911 calls. If they had gone outside, we would have eye witnesses. There are several additional facts after further voice analysis. First, I am greatly concerned about why Zimmerman did not listen to the 911 operator and wait for police. Could it have been because he didn’t want a suspicious character that may have been guilty of a breaking and entering crime to “get away with it”? I am also forensically concerned about how Zimmerman’s voice changed during the 911 call: specifically, the concern he expressed to the 911 operator which is recorded “these assholes always get away.” He made this statement in a very resentful vocal tone which is different from the sincere vocal tone he had at the beginning of the call. Then after giving police directions, he mumbled something under his breath (which I believe is not a positive phrase and is derogatory). Why the altercation? Police were less than 5 minutes away and would have handled the situation.  Zimmerman could have just followed Trayvon and helped police apprehend him. Then the big question, why did Zimmerman shoot to kill? He could have shot Trayvon in the shoulder or foot to maim him and keep him from getting away. Instead he shot to kill him. This is not a theory, this is a fact. So since there have been no formal charges, the people of the United States have taken sides. This is exactly what we did not want to happen. Protests continue across the country. The media has taken over as our judicial system because our legal system has failed us. I believe it is important to know who cried for help. This single development may be the most important piece of information authorities have about the Trayvon Martin killing. If this were Trayvon crying for help, then why did Zimmerman lie and say it was him? Was he worried about the charges? Up to this point, I have not been paid a dime for my time or my preliminary testing. I did this preliminary voice identification work in an attempt to help a difficult situation. Here are the forensic steps I have taken to analyze the 911 audio recordings. First, I critically listened to the calls and made several observations about the voices in two of the calls (George Zimmerman’s call and the woman’s call with the screaming and gunshot) and noted speech and voice characteristics. I immediately believed that the cries for help were not George Zimmerman’s. The following day I conducted further testing. I created a back to back edited digital audio file using sections from the Zimmerman call and the screaming male. This is how I confirmed my initial opinion that the cry for help is not Zimmerman. Next I applied light equalization, noise reduction and compression to the Zimmerman call so that I could hear his words more clearly. I was listening for anything that might help me understand more about the audio recordings. This is when I observed the mumbling by George Zimmerman after giving the 911 operator directions. I also noticed how his attitude and mood changed while talking to the 911 operator.  These observations were all noted as I continued to make observations. Think about it, why would a guy with a loaded gun who was stalking someone suddenly turn into a victim? That’s what the Zimmerman team is claiming. Whatever Trayvon did was in self-defense. Heck, perhaps he tried to stand his ground too (of course 17 year old kids know all the laws that protect them, right?) And, silly him, he didn’t have a gun. A young man is dead, there is evidence that needs to be examined and additional testing that should be conducted. For forensics investigation to proceed, an exemplar needs to be created. If the court would step in and order Mr. Zimmerman to cooperate, an exemplar or sample of Mr. Zimmerman’s voice could be recorded and analyzed against the original cries for help. This sample would be created to be as identical to the original as possible. For example, place Mr. Zimmerman in the exact location where the altercation took place. A forensic expert would help orchestrate this exemplar recording process and direct Mr. Zimmerman to scream like the cries for help in the recorded 911 call. Those voice samples would be recorded using as many of the same electronics that were used in the original recording as possible. In a perfect world, the same phone and 911 call center would cooperate and help facilitate the recording. When complete, an audio forensic expert would conduct a formal voice identification test and report their findings. If Trayvon were alive, the same test could be conducted on his voice. It is my understanding that there are no Trayvon media (audio or video) recordings available other than his cell phone (which is better than nothing). Voice identification is an art and a science and is a valuable tool in litigation. If you would like to learn more about voice identification, one of my mentors, Mr. Steve Cain, wrote a great article which is published on Expert Pages: http://expertpages.com/news/voiceprint_identification.htm. photo credit: Trayvon Martin Rally-0113-14-Jul-2013-Manhattan via photopin (license)