The opinion of the court was delivered by: Judge Joan H. Lefkow
This matter is before the court on the government's motion in limine to admit cell site evidence and analysis through the testimony of Special Agent Joseph Raschke. (Dkt. #97.) On August 17, 2011, defendant Antonio Evans and two co-defendants were charged with conspiracy to kidnap in violation of 18 U.S.C. § 1201(c) (Count I) and kidnapping in violation of 18 U.S.C. § 1201(a)(1) (Count II).*fn1 (Dkt. #41.) The kidnapping allegedly took place on April 23 and 24, 2010. The government proposes to call Special Agent Raschke to testify about the operation of cellular networks and how to use historical cell site data to determine the general location of a cell phone at the time of a particular call. Applying a theory called "granulization," Special Agent Raschke proposes to testify that calls placed from Evans's cell phone during the course of the conspiracy could have come from the building where the victim was held for ransom.
On August 21 and 23, 2012, this court held an evidentiary hearing pursuant to Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786, 125 L. Ed. 2d 469 (1993), to determine whether the government's proposed evidence and analysis are admissible. After the hearing, Evans moved for disclosure of expert evidence under Federal Rule of Criminal Procedure 16. (Dkt. #122.) For the reasons set forth herein, the government's motion in limine (dkt. #97) will be granted in part and denied in part and Evans's motion (dkt. #122) will be denied as moot.
The admission of lay witness testimony is governed by Federal Rule of Evidence 701, which limits lay opinion testimony to that which is (1) rationally based on the witness's perception; (2) helpful to clearly understanding the witness's testimony or to determining a fact in issue; and (3) not based on scientific, technical, or other specialized knowledge within the scope of Rule 702. Fed. R. Evid. 701. The admission of expert opinion testimony is governed by Federal Rule of Evidence 702 and Daubert. See Bielskis v. Louisville Ladder, Inc., 663 F.3d 887, 893 (7th Cir. 2011). Rule 702 states that a witness who is qualified as an expert by knowledge, skill experience, training or education may testify in the form of opinion or otherwise provided that "(1) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (2) the testimony is based on sufficient facts or data; (3) the testimony is the product of reliable principles and methods; and (4) the expert has reliably applied the principles and methods to the facts of the case." Fed. R. Evid. 702. To admit expert testimony under this rule, the court must determine that (1) the witness is qualified; (2) the expert's methodology is scientifically reliable; and (3) the testimony will assist the trier of fact to understand the evidence or to determine a fact in issue. Myers v. Ill. Cent. R.R. Co., 629 F.3d 639, 644 (7th Cir. 2010).
In Daubert the United States Supreme Court set out four factors the court may consider when assessing the reliability of an expert's methodology, including (1) whether the theory is based on scientific or other specialized knowledge that has been or can be tested; (2) whether the theory has been subjected to peer review; (3) the known or potential rate of error and the existence of standards controlling the theory's operation; and (4) the extent to which the theory is generally accepted in the relevant community. Daubert, 509 U.S. at 593--94; see also Kumho Tire Co. v. Carmichael, 526 U.S. 137, 151, 119 S. Ct. 1167, 143 L. Ed. 2d 238 (1999).
The Rule 702 inquiry "is a flexible one." Daubert, 509 U.S. at 594. As such, "[d]eterminations on admissibility should not supplant the adversarial process; 'shaky' expert testimony may be admissible, assailable by its opponents through cross-examination." Gayton v. McCoy, 593 F.3d 610, 616 (7th Cir. 2010). The proponent of the testimony bears the burden of proving that the proffered testimony meets these requirements, and the Seventh Circuit grants the district court "wide latitude in performing its gate-keeping function." Bielskis, 663 F.3d at 894 (internal quotation marks and citation omitted).
The government has obtained what it alleges are the call data records for the phone registered to Evans during the time of the alleged conspiracy. The data contained in these records includes the date and time of calls originating from Evans's phone, the duration of each call, and the originating and terminating cell tower (also known as cell site) used by the phone to place the call. Using these records, Special Agent Raschke testified that he could apply the granulization theory to estimate the general location of Evans's phone during the time calls were placed. To understand the theory of granulization it is necessary to understand how a cellular network operates.
According to Special Agent Raschke, when a cell phone is in idle mode, it regularly communicates with cell towers in its network. Using radio frequency waves, the phone tries to determine which cell tower has the strongest signal. In urban areas, cell towers are often located on top of buildings or water towers. A cell tower emits radio frequency waves in all directions, providing cell phone coverage in a 360 degree radius around the tower. Three antennas typically comprise each tower; each antenna covers a 120 degree area. When a cell phone places a call, it typically connects to the tower in its network with the strongest signal. This is usually the tower nearest to the phone, although a variety of factors including physical obstructions and topography can determine which tower services a particular phone. Once the call reaches the tower, this interaction is recorded by the network provider. The call then proceeds to a mobile switching center, which may choose to reroute the call to a different tower based on network traffic. The call may also be rerouted to a different tower if the caller changes location during the duration of the call.These data are recorded by the network and maintained as call data records.
To determine the location of a cell phone using the theory of granulization, Special Agent Raschke first identifies (1) the physical location of the cell sites used by the phone during the relevant time period; (2) the specific antenna used at each cell site; and (3) the direction of the antenna's coverage. He then estimates the range of each antenna's coverage based on the proximity of the tower to other towers in the area. This is the area in which the cell phone could connect with the tower given the angle of the antenna and the strength of its signal. Finally, using his training and experience, Special Agent Raschke predicts where the coverage area of one tower will overlap with the coverage area of another.
Applying this methodology, Special Agent Raschke testified that he could estimate the general location of Evans's cell phone during an 18 minute period (from 12:54 p.m. to 1:12 p.m.) on April 24, 2010, during which time Evans's phone used two cell towers to place nine calls. According to Special Agent Raschke, based on his estimate of the coverage area for each of the antennas, the calls made from Evans's phone could have come from the location where the victim was held for ransom. In support, the government proposes to admit summary exhibit 6, which is a map of the two towers used by Evans's phone and a drawing of the estimated coverage overlap of the two towers. The building where the victim was held falls squarely within the coverage overlap of the two towers. (See Gov't Summ. Ex. 6.) In addition to this exhibit, the government also proposes to introduce maps indicating the location of cell towers used by Evans's phone in relation to other locations relevant to the crime (Gov't Summ. Exs. 1--5),*fn2 maps showing the topography of the area between the two towers indicated in summary exhibit 6 (Gov't Summ. Ex. 7--8), and a listing of the total number of calls placed by Evans's phone during the relevant time period that originated or terminated with one of the two towers (Gov't Summ. Ex. 9).*fn3
I. Admissibility of maps containing cell tower locations and other locations relevant to the crime As an initial matter, the government argues ...