Department profile · Mercer County

Mercer County Sheriff's Department

Reported as: Mercer Co Sheriffs DeptCounty sheriff

Jurisdiction context

Civil service jurisdiction

Discipline at this department is governed by the Title 4A civil service framework, matched to Mercer County on the New Jersey Civil Service Commission roster.

Read how the process works or the Title 4A glossary. Browse NJCSNavigator’s civil service jurisdiction directory for the full local-jurisdiction roster.

Reflects the NJCSC Appendix A roster as of 2026-07-04. Context only, not legal advice.

Radio encryption

Mercer County Sheriff's Department encrypts its radio communications (P25 AES-256, part of its operations (All Operations except park rangers TG)), according to PoliceRadioEncryption.com, as of 2026-04-21 (unverified).

AnalysisThis site treats radio encryption as a meaningful transparency signal. When a department closes its radio traffic to the public, the public loses a real-time window into how it operates. That is context for reading the discipline and internal affairs records on this page, not a figure drawn from them.

Officers named in IA cases, 2025

4^{^[1]}

Distinct officers in that year's IA investigations, not total staffing

IA investigations, 2025

4^{^[1]}

Incidents, 2025

4^{^[1]}

Major discipline records

All years, 2020-2025

Staffing

Staffing data not available. The FBI's national staffing census (LEE) does not separately track county corrections facilities, sheriff's offices, or other county agencies in New Jersey -- only a single statewide Department of Corrections figure exists in that data. See the methodology for what FBI staffing data does and does not cover.

Military surplus equipment (1033 program)

No 1033 transfers recorded. No surplus-equipment transfers appear for this agency under a high-confidence name match in the Defense Logistics Agency's file as of 2026-06-30. That can mean the agency received nothing through the program, or that a recipient name in the federal file did not confidently match this department. See the methodology for how the match is made, or the statewide 1033 overview for how the program spreads across New Jersey.

Internal affairs investigations by year

counts

Internal affairs investigations reported by Mercer County Sheriff's Department, by year
Category	counts
2021	5
2022	21
2023	18
2025	4

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Incidents

4 in 2025

Internal affairs incidents reported by Mercer County Sheriff's Department, by year
Year	counts
2021	4
2022	20
2023	17
2025	4

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Analysis

Computed by this site from the two figures the agency reports each year. Not a misconduct rate: it describes how an agency resolved what it investigated.

share of total · 4 reported years

Share of internal affairs investigations sustained by Mercer County Sheriff's Department, by year
Year	share of total
2021	0
2022	66.667
2023	50
2025	75

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Statewide, 19.5 percent of investigations reported a sustained complaint in 2025. How dispositions break down statewide.

Complaint mix, 2025

Most serious allegation per investigation, as categorized by the reporting agency. Officer-level rows list 4 officers involved.

Most serious allegation

Most serious allegations reported by Mercer County Sheriff's Department, 2025
Other Departmental Rule Violation	2
Improper Arrest	1
Demeanor	1

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AdministrativeConduct / dutyRights / integrityViolence / criminal

Statewide category pages: Other Departmental Rule Violation · Improper Arrest · Demeanor

Internal disposition

Internal dispositions reported by Mercer County Sheriff's Department, 2025
Sustained	3
Unfounded	1

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Allegations by year, 2021 to 2025

AnalysisRanked and folded by this site. The counts inside each panel are as reported.

Other Departmental Rule Violation

16 of 48

Other Departmental Rule Violation allegations reported by Mercer County Sheriff's Department, by year
Year	counts
2021	4
2022	3
2023	7
2024	not reported
2025	2

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Attendance issues

12 of 48

Attendance issues allegations reported by Mercer County Sheriff's Department, by year
Year	counts
2021	0
2022	9
2023	3
2024	not reported
2025	0

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Demeanor

8 of 48

Demeanor allegations reported by Mercer County Sheriff's Department, by year
Year	counts
2021	1
2022	4
2023	2
2024	not reported
2025	1

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Neglect of Duty

3 of 48

Neglect of Duty allegations reported by Mercer County Sheriff's Department, by year
Year	counts
2021	0
2022	2
2023	1
2024	not reported
2025	0

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Other (7 categories)

9 of 48

Other (7 categories) allegations reported by Mercer County Sheriff's Department, by year
Year	counts
2021	0
2022	3
2023	5
2024	not reported
2025	1

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Against peers, 2025

How this grade was built →

Internal affairs investigations per 100 IA-investigated officers, 2025 (investigations per 100 IA-investigated officers)
Mercer County Sheriff's Department	100.0
County median, county sheriff (1)	100.0
NJ median, county sheriff (20)	115.2

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Investigations per 100 officers named in that year's IA investigations (the Attorney General's own "Number of Officers" field, a distinct-officer count drawn from the IA case data itself, not a department headcount). A higher number is ambiguous on its own: it can reflect more misconduct, or a stronger internal reporting culture. Medians are computed within the same agency type only.

Report card

Grade B: Second-lowest fifth

On reported IA volume and discipline severity; see methodology

Combined standing: 36th percentile of 21 peers
Confidence: Medium confidence

small agency; per-officer rates swing widely on a handful of cases

Where this agency falls among its peers

The actual spread of discipline severity across Mercer County Sheriff's Department's real peer group, not an assumed bell curve. If the group is skewed, it is shown skewed.

Peer group: County sheriff, all sheriff agencies (n=21)

Discipline severity: County sheriff, all sheriff agencies
Range	Agencies
0–50	6
50–100	8
100–150	6
150–200	0
200–250	1

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Mercer County Sheriff's Department: 76.19 severity-weighted discipline per 100 IA-investigated officers: 60th percentile among County sheriff, all sheriff agencies (n=21).

How the grade is built

Three components, each a percentile within the peer group. The combined standing is their weighted mean, re-ranked among peers; the grade is the fifth of the peer group it lands in.

IA volumeweight 40%

40th percentileof 21 peers

109.0 investigations per 100 officers (multi-year mean)

Internal affairs investigations per 100 reported officers, averaged over the years where the agency reported both figures.

Discipline severityweight 40%

60th percentileof 21 peers

76.2 severity-weighted discipline per 100 officers, 2020-2025

Major discipline records weighted by sanction (termination 4, demotion 3, suspension 2, other 1) per 100 officers.

Allegation severityweight 20%

21st percentileof 21 peers

1.51 mean severity tier (1 low - 4 critical)

Mean severity tier of IA allegations across 2021-2025, using the published tier map; unknown values excluded.

What this grade can and can't tell you

The underlying data is self-reported by agencies, one yearly snapshot at a time.
Allegations are not findings; many complaints end unfounded, exonerated, or not sustained.
There is no arrest or call-volume denominator in this data, so nothing here is a per-capita misconduct rate. A genuinely independent staffing-based rate, sourced from the FBI rather than this grade's own data, appears above when available. It is a different measurement, not a more accurate version of the grade.
A higher internal affairs volume is ambiguous: it can indicate more misconduct, or a more robust oversight and reporting culture. The grade weighs it anyway, because volume is what the record offers; that choice is published, not hidden.
The grade is one lens. The records it reads are on this page above.

Where this agency ranks

AnalysisRankings compare agencies of the same type only, on figures as reported. A high rank is reported volume, not a verdict.^[13] How each metric is defined.

This agency's rank on each metric, among agencies of the same type
Metric	Value	Rank
IA per 100 investigated officers2025	100.0	15th of 20 county sheriff
IA investigations2025	4	17th of 20 county sheriff
IA incidents2025	4	16th of 20 county sheriff
Major discipline2020-2025	4	11th of 17 county sheriff

Major discipline records

0 major discipline records in 2025, down from 2 in 2020 (-100%).
Year	major discipline records
2020	2
2021	0
2022	0
2023	0
2024	2
2025	0

0 major discipline records in 2025, down from 2 in 2020 (-100%).

Major discipline records reported by Mercer County Sheriff's Department, 2020-2025
Year	Officer	Rank	Sanction as reported	Src
2024	Elizabeth Roberts	Officer	Suspended 30 days	^[14]
2024	Matthew Sickler	Officer	Suspended 256 daysSeparated while IA pending	^[15]
2020	Christopher Gregg	Officer	Suspended 6 days	^[16]
2020	Christopher Gregg	Officer	Suspended 12 days	^[17]

Every name links to the officer's record page with the agency's full synopsis and citation.

Fatal encounters recorded involving this agency

From the independent Fatal Encounters dataset, 2000-2021

In brief (written by this site from the records below)

Three records in the Fatal Encounters dataset name Mercer County Sheriff's Department, spanning 2001 through 2018. The force labels, as recorded by the project, are Gunshot in three of them. Fatal Encounters is an independent, crowdsourced journalism project that documented deaths occurring during police encounters of any kind, including vehicle pursuits, deaths in police presence, and medical emergencies. A record is not a finding of fault against the agency or any officer, and it is not connected to the Attorney General discipline records elsewhere on this page. The project stopped collecting in December 2021, so the dataset is frozen and nothing after that date appears here.

Fatal Encounters is an independent, crowdsourced dataset that documented deaths during police encounters nationwide from 2000 until its collection ended in December 2021.^[2] It records all deaths that occurred during a police encounter of any kind: vehicle pursuits, suicides in police presence, and medical emergencies are included alongside uses of force. A record appears here because Mercer County Sheriff's Departmentis named in the record's as-reported agency field. A listing is not a misconduct finding, and it is not connected to the Attorney General discipline records above. See the methodology. Each record links to its own page with the full as-reported details.

Scott Mielentz
March 20, 2018 · Princeton · Highest level of force as recorded: Gunshot
Robert Powell Jr.
May 10, 2017 · Trenton · Highest level of force as recorded: Gunshot
Danny Larkin
June 30, 2001 · Hamilton Township · Highest level of force as recorded: Gunshot

Public records requests

No records-request history is shown for this department. OPRAmachine, an independent site that files and publishes Open Public Records Act requests, has no public body that confidently matches this department, so this site does not assert one. That does not mean nobody has requested records from it. (Checked against a snapshot of OPRAmachine taken 12 July 2026.) See the methodology for how the match is made.

Questions and answers

How many internal affairs investigations did Mercer County Sheriff's Department report in 2025?

Mercer County Sheriff's Department reported 4 internal affairs investigations in 2025, according to New Jersey Attorney General data. 4 distinct officers were named in that year's IA investigations.

How many major discipline records does Mercer County Sheriff's Department have?

Mercer County Sheriff's Department has 4 major discipline records in the Attorney General's 2020-2025 releases, of which 0 were terminations. These are final, adjudicated actions, not allegations.

Does Mercer County Sheriff's Department encrypt its radio communications?

According to PoliceRadioEncryption.com, Mercer County Sheriff's Department encrypts part of its radio communications (P25 AES-256), as recorded on 2026-04-21. This site treats radio encryption as a transparency signal, which is analysis, not a figure from the discipline data.

How many deaths during police encounters are recorded for Mercer County Sheriff's Department?

The independent Fatal Encounters dataset contains 3 records naming Mercer County Sheriff's Department, from 2001 through 2018. Fatal Encounters is a crowdsourced journalism project, not a government source, and it documented deaths that occurred during police encounters of any kind. Each record links to a page showing it exactly as the project recorded it.

Sources

[1]New Jersey Internal Affairs Agency Totals, 2021-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 2295. Snapshot retrieved 2026-06-09. ↩
[2]Fatal Encounters, New Jersey subset. Fatal Encounters (fatalencounters.org). Fatal Encounters national dataset (2000-2021); collection ended December 2021. Retrieved 2026-07-10. https://fatalencounters.org/ ↩
[3]New Jersey county boundaries. New Jersey Office of Information Technology, Office of GIS (NJOGIS). NJ_Counties_3857 (FeatureServer layer 0), https://services2.arcgis.com/XVOqAjTOJ5P6ngMu/arcgis/rest/services/NJ_Counties_3857/FeatureServer/0. 2020 boundary delineation. Retrieved 2026-07-27. Boundaries are generalized for display. This data set is not a survey document and must not be used as such. The polygons do not represent legal boundaries.
[4]New Jersey Internal Affairs Agency Totals, 2021-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 263. Snapshot retrieved 2026-06-09. ↩
[5]New Jersey Internal Affairs Agency Totals, 2021-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1280. Snapshot retrieved 2026-06-09. ↩
[6]New Jersey Internal Affairs Agency Totals, 2021-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1783. Snapshot retrieved 2026-06-09. ↩
[7]New Jersey Internal Affairs Agency Totals, 2021-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 2295. Snapshot retrieved 2026-06-09. ↩
[8]New Jersey Internal Affairs Investigations, 2024-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1. Snapshot retrieved 2026-06-09. Aggregated from every Mercer Co Sheriffs Dept row for 2025; row 1 is the header. ↩
[9]New Jersey Internal Affairs Data Download, 2021-2023. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1. Snapshot retrieved 2026-06-09. Aggregated from every Mercer Co Sheriffs Dept row for 2021. ↩
[10]New Jersey Internal Affairs Data Download, 2021-2023. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1. Snapshot retrieved 2026-06-09. Aggregated from every Mercer Co Sheriffs Dept row for 2022. ↩
[11]New Jersey Internal Affairs Data Download, 2021-2023. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1. Snapshot retrieved 2026-06-09. Aggregated from every Mercer Co Sheriffs Dept row for 2023. ↩
[12]New Jersey Internal Affairs Investigations, 2024-2025. New Jersey Office of the Attorney General. Sheet "Sheet1", row 1. Snapshot retrieved 2026-06-09. Aggregated from every Mercer Co Sheriffs Dept row for 2025. ↩
[13]Ranks computed by this site over the Attorney General internal affairs agency totals and major discipline releases, within agency type. Each ranking page lists every agency and its source rows. ↩
[14]New Jersey Major Discipline Data, 2020-2025. New Jersey Office of the Attorney General. Sheet "Major Discipline Data", row 1148. Snapshot retrieved 2026-07-03. ↩
[15]New Jersey Major Discipline Data, 2020-2025. New Jersey Office of the Attorney General. Sheet "Major Discipline Data", row 1149. Snapshot retrieved 2026-07-03. ↩
[16]New Jersey Major Discipline Data, 2020-2025. New Jersey Office of the Attorney General. Sheet "Major Discipline Data", row 2875. Snapshot retrieved 2026-07-03. ↩
[17]New Jersey Major Discipline Data, 2020-2025. New Jersey Office of the Attorney General. Sheet "Major Discipline Data", row 2876. Snapshot retrieved 2026-07-03. ↩