Person Nicholas Guarino Trial 1Trial 2Massachusetts State Police digital forensics trooper who extracted and analyzed phone data from multiple devices central to the case, including O’Keefe’s, Read’s, and Jennifer McCabe’s phones. ← All People
🔬 Expert Witness · MSP

Nicholas Guarino

Trial 1Trial 2
1,057 lines 7 proceedings 2 trials
Courtroom still of Nicholas Guarino.

About

Trooper Nicholas Guarino is a Massachusetts State Police digital forensics examiner who testified in both trials about phone extractions, GPS data, call logs, text messages, and health data from devices belonging to John O'Keefe, Karen Read, Kerry Roberts, and Jennifer McCabe. His testimony covered the timeline of Read's movements on the night of January 28–29, 2022, and directly rebutted defense expert Richard Green's analysis of McCabe's phone data. In Trial 1 he also addressed the failed extraction of Read's Lexus infotainment system and presented velocity calculations arguing O'Keefe could not have entered 34 Fairview during a brief GPS anomaly window.

Key Points

  • Guarino presented Apple Health data showing O'Keefe's phone recorded stair climbs between 12:22 and 12:24 a.m. at a location the prosecution placed near Maple Croft and Pine Cone — a half mile from 34 Fairview — which became a focal point for both sides in arguing where O'Keefe was in the minutes after leaving Read's car.
  • Guarino testified that Read's phone auto-connected to O'Keefe's password-protected Wi-Fi at 1 Meadows Avenue at 12:36 a.m. Separately, he read messages in which Read said she was going home and then was back in Mansfield; the Wi-Fi location and the reported Mansfield location were distinct.
  • Guarino performed a velocity calculation showing that for O'Keefe to have entered 34 Fairview and returned during a brief GPS accuracy fluctuation, he would have needed to travel at approximately 32 miles per hour — which Guarino stated was not supported by any health or motion data.
  • In Trial 1, Guarino systematically went through defense expert Richard Green's report point by point, testifying that it was 'mostly incorrect,' specifically rebutting Green's claims about the timing of McCabe's 'how long to die in cold' Google search and the significance of 18 call log entries Green characterized as deleted.
  • Guarino confirmed that despite employing Berla vehicle infotainment extraction technology and a chip-off attempt, no data was recovered from Read's Lexus, leaving no electronic record of the vehicle's movements on the night in question.

Trial Record (7)

Trial 1 First Criminal Trial Apr 29, 2024 – Jul 1, 2024 4 proceedings

Day 26

Direct Nicholas Guarino Adam Lally 2 highlights 196 lines spoken
Summary

Trooper Nicholas Guarino described failed Lexus data-recovery efforts, disputed an interpretation of Jennifer McCabe's phone data, and authenticated phone-message and call-log records.

Highlights (2)
Quote

“The trim level that the defendant had is not still supported. There is Toyota and Lexus support now, but it's not, unfortunately, for her model.”

Explains the stated limitation on obtaining readable data from the Lexus infotainment system.

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Quote

“Yeah, so he stated that Ms. McCabe had deleted 18 phone calls from the morning after John O'Keefe's body was found. Looking at the data from her call log, those calls, while they do show marked as deleted, again, they come from the WAL file, and they're also located in two other parts of the database. Again, as a user of an iPhone, you can't go in and just delete these files. They're handled by the operating system. It's impossible.”

States Guarino's technical basis for disputing the claimed user deletion of the cited call records.

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Day 28

Direct Nicholas Guarino Adam Lally 2 highlights 183 lines spoken
Summary

Guarino presented phone, voicemail, and location-data evidence; Judge Cannone excluded a Google search for DUI attorneys from the Commonwealth's case-in-chief.

Highlights (2)
Quote

“So by looking at the timeline in the phone, we were able to see that Ms. Read's phone auto-connected to John O'Keefe's WiFi at his house at 12:36 a.m.”

Guarino identified a time-stamped phone connection to O'Keefe's home Wi-Fi.

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Key Moment

Guarino described O'Keefe's phone location data, including a Waze search for 34 Fairview, the route to that area, and phone points that he said remained between 32 and 34 Fairview overnight.

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Cross Nicholas Guarino David Yannetti 2 highlights 329 lines spoken
Summary

Defense counsel challenged Guarino's phone-data analysis, reporting, and evidence handling through location, timestamp, call-log, and extraction records.

Highlights (2)
Quote

“No. Again, like I said, the phone is a high tech pedometer. It doesn't mean that steps were taken. It means the phone was manipulated in a way that it believed it was moving and taking steps.”

Guarino explained his qualification on the meaning of Apple Health step data.

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Quote

“I didn't look at any specific calls that morning. I created a Cellebrite report. That's about it.”

Guarino described the limited scope of his own review of the call records at issue.

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Redirect Nicholas Guarino Adam Lally 2 highlights 42 lines spoken
Summary

Guarino defended his interpretation of disputed phone-search and WAL-file data, then testified about search-related cookies found on the defendant's phone.

Highlights (2)
Quote

“Well, it's physically impossible to search two things at once.”

Guarino stated the basis of his opinion that the disputed searches did not occur at 2:27 a.m.

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Quote

“Again, the user has no input on how a WAL file is deleted. It's an automated thing that the database does to clean up.”

Guarino gave his explanation for why WAL-file entries could be marked deleted without user action.

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Trial 2 Retrial Apr 22, 2025 – Jun 18, 2025 3 proceedings

Day 2

Direct Nicholas Guarino Hank Brennan 4 highlights 164 lines spoken
Summary

Trooper Nicholas Guarino testifies about his digital forensics background and the process of extracting data from phones belonging to John O'Keefe, Karen Read, Kerry Roberts, and Jennifer McCabe.

Highlights (4)
Quote

“Even if it's just a period, yes, any alteration to that initial extraction, with that number it immediately would change.”

Explains hash value integrity verification — the core mechanism prosecutors use to prove phone data was not tampered with.

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Quote

“These reports are finding the low-hanging fruit in the proverbial tree. So, that's showing you the stuff that the program has set that most people are looking for.”

Acknowledges that standard forensic tools surface obvious data first, with deeper analysis requiring additional software and corroboration.

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Quote

“No, it wasn't supported by GrayKey, the phone model and number.”

Explains why Read's phone could not be immediately accessed, requiring a wait until July 2022 for software to advance enough to brute-force the passcode.

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Quote

“I would wait for a request. Again, my knowledge of most of the cases is very limited.”

Establishes Guarino's role as a technician executing requests rather than directing the investigation — relevant to questions about what was and wasn't examined.

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Day 3

Direct Nicholas Guarino Hank Brennan 3 highlights 97 lines spoken
Summary

Trooper Guarino introduces phone extraction reports and reads extensive text messages between Karen Read and John O'Keefe from January 28, 2022, followed by video clips of Read discussing her drinking that night.

Highlights (3)
Quote

“If the call is not answered, that means the call rang out and goes to voicemail. If the call is rejected, that is someone actively hitting the send-to-voicemail button to disable the call — to stop it from ringing.”

Establishes technical distinction that O'Keefe was actively rejecting Read's calls, not simply missing them

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Quote

“Sick of always arguing and fighting. It's been weekly for several months now. So, yeah, I'm not as quick to jump back into being lovey-dovey as you, apparently.”

O'Keefe's characterization of the relationship as one with chronic conflict

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Quote

“From the defendant to John O'Keefe, I think the four of us together is toxic to this relationship. Would like to limit it.”

Read's stated view that the dynamic with O'Keefe's children was damaging their relationship

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Day 10

Direct Nicholas Guarino Hank Brennan 3 highlights 46 lines spoken
Summary

Trooper Guarino presents a chronological PowerPoint of Karen Read's calls, texts, and voicemails to John O'Keefe from 12:33 a.m. to 6:03 a.m. on January 29, 2022.

Highlights (3)
Quote

“At 12:36:09 a.m., the defendant's phone auto-connects to the Wi-Fi PatsFan123.”

Records the 12:36:09 a.m. auto-connection and the named PatsFan123 network; the connection does not by itself establish an exact phone-to-home distance.

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Quote

“Depending on which one it's connecting to, which band, it's either 150-foot indoor range or up to 300 feet outdoor. So, again, when you pull into your home, sometimes you can still be connected to your home Wi-Fi in the driveway.”

Describes generic indoor and outdoor ranges that depend on the router band. Guarino had not inspected the router in person and did not identify its actual band.

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Quote

“Defendant texts John O'Keefe: "I'm back in Mansfield. The kids are home alone." 1:04:14 a.m. on the 29th.”

Text message places Read claiming to be back in Mansfield at 1:04 a.m., part of the prosecution's timeline reconstruction.

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