Murder Case is First Knox County Case to Involve Drive Test Analysis of Cell Tower Pings

Here’s an interesting story about a murder case out of Tennessee. According to the article,

In a legal first for Knox County, a judge will allow testimony on a controversial FBI cellular analysis method in the case of a man accused of killing his pregnant girlfriend.

32 year-old Norman Eugene Clark is charged with two counts of first-degree murder in connection with the death of Brittany Eldridge, 25, and the couple’s unborn son, Ezekiel. Back in February, the bond that Clark could post for pre-trial release was reduced from $1 million to $500,000.

Eldridge was 81/2 months pregnant with Ezekiel when in December 2011 she was found stabbed, beaten and strangled inside her home at the Cross Creek apartment complex off Western Avenue.

According to the article,

There were no witnesses to the crime or DNA evidence tying Clark to the slayings. The Knoxville Police Department enlisted the aid of the FBI’s Cellular Analysis Survey Team, a relatively new task force that has made its mark with such cases as the Boston Marathon bombing.

t is controversial because of the assumptions the team relies upon and its mix of old cellphone data and current tower signal strength. FBI Agent Kevin Horan testified at a hearing Friday the analysis is based on the belief a cellular phone will, with rare exception, choose a tower with the strongest signal near where the phone is being used.

The team then takes information about the phone’s use from the cellular service provider. Agents then conduct a “drive test” to determine the signal strength of the tower at issue at the time of the test, not the crime. With that method, the FBI can show a suspect’s location within a two-mile radius.

Those who listen to the Undisclosed Podcast will recall that there are serious questions about drive tests and the “rare exception” and two mile radius claims. Nonetheless, Horan claims that

he was able to show Clark was not, as he claimed, at his home at the time of the slayings and instead was within the radius around Eldridge’s apartment.

Meanwhile, defense counsel

has an expert of his own who is part of a team that travels the country testifying against the FBI’s CAST agents and their findings.

Those experts contend cellphone signals do not always use the closest tower but instead are routed by a computerized switching center to the tower that best serves the phone network, and a tower’s range varies widely.

It will be interesting to see how this case unfolds. In particular, I’m interested in the distance between Eldridge’s apartment, Clark’s home, and the relevant cell towers pinged. 

One last point: Tennessee is a Daubert jurisdiction.

-CM