InterVentis is a practitioner-led network. The people below hold the doctrine, carry the cases, and answer the phone when it matters most.
Timo der Weduwen
Founding Principal - Doctrine & Practice Lead
Strängnäs - Sweden
As an adviser to the United Nations, governments, international organisations and the private sector for more than three decades, Timo brings deep experience in security risk management, crisis management and the response to critical incidents to the InterVentis team. A former senior United Nations security official, he has worked extensively in fragile, conflict-affected and high-risk environments, where he has managed security operations and supported organisations through serious and complex crises.
Timo specialises in kidnapping, hostage-taking and other forms of coercive detention. Trained as a hostage negotiator by Scotland Yard, he brings considerable practitioner experience in responding to international kidnappings and hostage incidents, including complex kidnap-for-ransom cases and hostage negotiations. His work has involved advising and supporting senior decision-makers, managing negotiation strategies, working with families, and coordinating with governments, law enforcement agencies, international organisations and other stakeholders during incidents where decisions can have direct consequences for the lives and safety of those involved.
He is the programme director and principal author of KRIM™, the accredited Kidnap for Ransom Incident Management Programme, through which he has helped develop professional incident-management capability across the United Nations, international organisations, NGOs and the private sector. He combines operational experience with a strong focus on professional judgement, negotiation, doctrine and human-centred crisis management, particularly where organisations must make difficult decisions under conditions of uncertainty, pressure and risk to life.
Frans Barnard
Founding Principal
Yellowknife, Northwest Territories, Canada
Frans is a Certified Kidnap & Ransom Manager with over 20 years of senior humanitarian leadership experience in conflict-affected environments, including Gaza, Somalia, Yemen and Nigeria. He has worked with global INGOs, UN bodies and specialist Kidnap and Ransom response organisations, supporting the management and resolution of complex kidnapping cases in some of the world’s most challenging operational contexts.
His expertise is grounded in under / un governed environments where law enforcement is limited, fragmented or ineffective. Frans applies structured, legally compliant negotiation strategies informed by a deep understanding of local conflict dynamics, political sensitivities and cultural realities. He recognises that no two incidents are the same and tailors his approach accordingly — balancing disciplined process with pragmatic judgement to secure safe and responsible outcomes all the while ensuring the victims and their families remain central to any response.
Frans has advised senior organisational and government decision-makers during high-pressure kidnap incidents, providing clear strategic guidance while ensuring that the welfare of victims and their families remains central to the response. His experience enables him to navigate the institutional, legal and reputational complexities that accompany such cases, aligning operational action with governance and duty-of-care obligations.
A former Infantry Officer in the British Army with a Master’s degree in Human Security & Peacebuilding, Frans combines operational field experience with strategic insight. His ability to analyse complex environments, negotiate under pressure and integrate multiple stakeholder interests positions him as a trusted professional in the field of kidnap incident management and resolution
Graham Mathieson
Founding Principal
Exeter, UK
Graham has spent the past 20 years helping people and organisations through crises in some of the world’s most challenging environments. His strength lies in making sense of fast-moving situations, identifying what matters and helping people decide how to move forwards with certainty. He brings calm and structure when information is incomplete, emotions are intense and decisions have real consequences.
A qualified Kidnap Incident Manager, Graham has supported organisations responding to kidnappings, arbitrary detentions and other threats to life across Africa and the Middle East. His case experience includes incidents in Nigeria, Somalia, Mozambique and Ethiopia, working with leaders, colleagues and affected families to help them regain control and move towards a safe and responsible resolution.
A former British Army officer, Graham has held senior security and crisis management roles with humanitarian organisations and advised humanitarian, diplomatic, media and commercial clients. His experience includes armed conflict, civil unrest, disease outbreaks and crises.
Graham holds a Master’s degree in Organisational Psychology, complementing his understanding of problem-solving under pressure, team & organisational dynamics and psychological safety. He also develops crisis plans, delivers realistic simulation exercises and helps teams learn honestly from serious incidents and their aftermath. His approach is practical, discreet and human. He helps clients prepare before an incident, think clearly during it and recover afterwards, while keeping the safety and wellbeing of those affected at the centre of every decision.
Ruben Hoornveld
Founding Principal
Ho Chi Minh City, Vietnam
Ruben brings more than 30 years of experience in crisis response, security and crisis communications to the InterVentis team, having worked across more than 35 countries and a range of military, government, humanitarian, development, maritime and private-sector environments. A former officer in the Royal Netherlands Army, he has extensive experience operating in fragile, conflict-affected and high-risk environments.
Ruben specialises in the response to kidnapping, extortion, wrongful detention and threats to life. He has supported organisations and senior decision-makers through complex and high-pressure incidents, providing practical guidance on incident management, stakeholder engagement and crisis communications. His approach combines structured response with pragmatic judgement, particularly in environments where governance and law enforcement capacity may be limited or fragmented.
His broader crisis response experience includes managing critical incidents across diverse operating environments, with a focus on protecting life, supporting informed decision-making and helping organisations navigate the operational, human and reputational pressures that accompany serious incidents.
Philippe Gourdin
Founding Principal
Mallorca, ESP
Philippe brings the discipline of a risk manager, the grounding of a qualified incident manager, and the diplomatic capability to work channels outside conventional architecture, the network and mediation capacity to move a crisis toward resolution. With a career built on the risk management side of crisis response, not the security side. As a qualified Kidnap for Ransom Incident Manager, he has responded directly to kidnapping, and wrongful detention, working inside the pressure these situations create for leadership.
His specific value lies at the intersection of diplomacy, mediation, and negotiation. Where many response structures rely on security and operational protocol alone, Philippe adds a dimension too often missing: the ability to engage political, governmental, and private-sector actors directly, and to move a case forward through relationships formal structures cannot always reach. This network, built over years across multiple regions, is core to what InterVentis offers clients.
That capability has been tested in demanding environments. Philippe's work alongside the United Nations, the World Bank, and the ICRC has given him practitioner-level experience of complex, high-risk, politically sensitive situations.
Sean Evanko
Founding Principal · Negotiation Adviser
Lisbon, Portugal
Sean brings a strong commercial and client-facing perspective to the InterVentis team, built over seventeen years in relationship management and marketing across the United States, Europe, South East Asia, South Pacific and Indian Ocean territories. Working directly with client-side owners, CMOs and growth leads, his focus is on understanding client needs and ensuring InterVentis services remain relevant, accessible and responsive to the organisations it supports.
Certified through both the Kidnap for Ransom Incident Management (KRIM) Programme and The Negotiator Programme (TNP), Sean has a grounded understanding of the principles, structures and disciplines that underpin effective response to kidnapping and other critical incidents. He combines this knowledge with a particular focus on client experience, helping to connect specialist response capability with the organisations and decision-makers who may need it.
Within InterVentis, Sean focuses on client engagement, partnerships, business development and the continuous improvement of the client experience.
